a summary of our capital expenditures for the last three years is as follows : replace_table_token_4_th ( a ) includes capital expenditures recorded as a result of certain ccic transactions that result in permanent improvements to our towers . we are not a party to such transactions , and do not make cash payments in connection with such transactions . capital expenditures increased by approximately $ 15.7 million from 2018 to 2019 predominately due to a higher volume of improvements performed on existing sites . 18 financing activities the net cash flows used for financing activities during the years ended december 31 , 2019 and 2018 were impacted by our continued practice of distributing excess cash to our member . see note 7 to our consolidated financial statements . contractual cash obligations the following table summarizes our contractual cash obligations as of december 31 , 2019 . these contractual cash obligations relate primarily to our 3.849 % secured notes and lease obligations for land interests under our towers . replace_table_token_5_th ( a ) the following items are in addition to the obligations disclosed in the above table : we have a legal obligation to perform certain asset retirement activities , including requirements upon lease and easement terminations to remove sites or remediate the land upon which our site resides . the cash obligations disclosed in the above table , as of december 31 , 2019 , are exclusive of estimated undiscounted future cash outlays for asset retirement obligations of approximately $ 82.6 million . as of december 31 , 2019 , the net present value of these asset retirement obligations was approximately $ 11.4 million . see note 10 to our consolidated financial statements . we are contractually obligated to pay or reimburse others for property taxes related to our sites . ccic has the option to purchase approximately 68 % of our sites that are leased or subleased or operated and managed under sprint master leases at the end of their contract term . ccic has no obligation to exercise the purchase option . see note 1 to our consolidated financial statements . we have legal obligations for open purchase order commitments obtained in the ordinary course of business that have not yet been fulfilled . ( b ) amounts relate primarily to lease obligations for the land interests on which our towers reside and are based on the assumption that payments will be made for certain renewal periods exercisable at our option that are reasonably certain to be exercised and excludes our contingent payments for operating leases ( such as payments based on revenues derived from sites located on the leased asset ) as such arrangements are excluded from our operating lease liability . see note 11 to our consolidated financial statements for a further discussion of our operating lease obligations . debt restrictions the secured notes indenture does not contain financial maintenance covenants but it does contain restrictive covenants , subject to certain exceptions , related to our ability to incur indebtedness , incur liens , enter into certain mergers or change of control transactions , sell or issue equity interests , and enter into related party transactions . with respect to the restriction regarding the issuance of debt , we may not issue debt other than ( 1 ) certain permitted refinancings of the 3.849 % secured notes , ( 2 ) unsecured trade payables in the ordinary course of business and financing of equipment , land or other property up to an aggregate of $ 100.0 million or ( 3 ) unsecured debt or additional notes under the secured notes indenture provided that the debt to adjusted consolidated cash flow ratio ( as defined in the secured notes indenture ) at the time of incurrence , and after giving effect to such incurrence , would have been no greater than 3.5 to 1. as of december 31 , 2019 , our debt to adjusted consolidated cash flow ratio was 2.3 to 1 , and , as a result , we are currently not restricted in our ability to incur additional indebtedness . for purposes of restrictions related to our secured notes indenture , relevant debt calculations ( such as our debt to adjusted consolidated cash flow ratio ) are calculated in accordance with gaap that was in effect as of december 2012 , and , as such , exclude the impact of our lease liability recorded as a result of our new lease standard adoption on january 1 , 2019. further , we are not restricted in our ability to distribute cash to affiliates or issue dividends to our member . accounting and reporting matters critical accounting policies and estimates our critical accounting policies and estimates are those that we believe ( 1 ) are most important to the portrayal of our financial condition and results of operations or ( 2 ) require our most difficult , subjective or complex judgments , often as a result of the need to make estimates about the effect of matters that are inherently uncertain . in many cases , the accounting treatment of a particular transaction is specifically prescribed by gaap . in other cases , management is required to exercise judgment in the application of accounting principles with respect to particular transactions . the critical accounting policies and estimates for 2019 are not intended to be a comprehensive list of our accounting policies and estimates . see note 3 to our consolidated financial statements for a summary of our significant accounting policies , including information related to our adoption of the new lease accounting guidance ( commonly referred to as `` acs 842 `` or `` new lease standard `` on january 1 , 2019 . 19 lease accounting - lessee . our lessee arrangements primarily consist of ground leases for land under our towers . story_separator_special_tag any purchase price in excess of the net fair value of the assets acquired and liabilities assumed is allocated to goodwill . the fair value of the vast majority of our assets and liabilities is determined by using either : 20 ( 1 ) estimates of replacement costs ( for tangible fixed assets such as sites ) , or ( 2 ) discounted cash flow valuation methods ( for estimating identifiable intangibles such as site rental contracts and tenant relationships or operating lease right-of-use assets and lease liabilities acquired ) . the purchase price allocation requires subjective estimates that , if incorrectly estimated , could be material to our consolidated financial statements , including the amount of depreciation , amortization and accretion expense . the most important estimates for measurement of tangible fixed assets are : ( 1 ) the cost to replace the asset with a new asset and ( 2 ) the economic useful life after giving effect to age , quality and condition . the most important estimates for measurement of intangible assets are ( 1 ) discount rates and ( 2 ) timing , length and amount of cash flows including estimates regarding tenant renewals and cancellations . the most important estimates for measurement of operating lease rou assets and lease liabilities acquired are ( 1 ) present value of our future lease payments , including whether renewals or extensions should be measured , and ( 2 ) favorability or unfavorability to the current market terms . we record the fair value of obligations to perform certain asset retirement activities , including requirements , pursuant to our ground contracts or easements , to remove sites or remediate the land upon which certain of our sites reside . in determining the fair value of these asset retirement obligations , we must make several subjective and highly judgmental estimates such as those related to : ( 1 ) timing of cash flows , ( 2 ) future costs , ( 3 ) discount rates and ( 4 ) the probability of enforcement to remove the towers or remediate the land . see note 3 to our consolidated financial statements . accounting for long-lived assets — useful lives . we are required to make subjective assessments as to the useful lives of our tangible and intangible assets for purposes of determining depreciation , amortization and accretion expense that , if incorrectly estimated , could be material to our consolidated financial statements . depreciation expense for our property and equipment is computed using the straight-line method over the estimated useful lives of our various classes of tangible assets . the substantial portion of our property and equipment represents the cost of our sites , which is depreciated with an estimated useful life equal to the shorter of ( 1 ) 20 years or ( 2 ) the term of the lease ( including optional renewals ) for the land interests under the towers . the useful life of our intangible assets is estimated based on the period over which the intangible asset is expected to benefit us and gives consideration to the expected useful life of other assets to which the useful life may relate . we review the expected useful lives of our intangible assets on an ongoing basis and adjust if necessary . amortization expense for intangible assets is computed using the straight-line method over the estimated useful life of each of the intangible assets . the useful life of the site rental contracts and tenant relationships intangible assets is limited by the maximum depreciable life of the site ( 20 years ) , as a result of the interdependency of the sites and site rental contracts and tenant relationships . in contrast , the site rental contracts and tenant relationships are estimated to provide economic benefits for several decades because of the low rate of tenant cancellations and high rate of renewals experienced to date . thus , while site rental contracts and tenant relationships are valued based upon the fair value of the site rental contracts and tenant relationships which includes assumptions regarding both ( 1 ) tenants ' exercise of optional renewals contained in the acquired leases and ( 2 ) renewals of the acquired leases past the contractual term including exercisable options , the site rental contracts are amortized over a period not to exceed 20 years as a result of the useful life being limited by the depreciable life of the sites . accounting for long-lived assets — impairment evaluation . we review the carrying values of property and equipment , intangible assets or other long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amounts may not be recoverable . we utilize the following dual grouping policy for purposes of determining the unit of account for testing impairment of the site rental contracts and tenant relationships : ( 1 ) we pool site rental contracts and tenant relationships intangible assets and property and equipment into portfolio groups ; and ( 2 ) we separately pool site rental contracts and tenant relationships by significant tenant or by tenant grouping for individually insignificant tenants , as appropriate . we first pool site rental contracts and tenant relationships intangible assets and property and equipment into portfolio groups for purposes of determining the unit of account for impairment testing , because we view sites as portfolios and sites in a given portfolio and its related tenant contracts are not largely independent of the other sites in the portfolio . we re-evaluate the appropriateness of the pooled groups at least annually . this use of grouping is based in part on ( 1 ) our limitations regarding disposal of sites , ( 2 ) the interdependencies of site portfolios and ( 3 ) the manner in which sites are traded in the marketplace . the vast majority of our site rental contracts and tenant relationships intangible assets and property and equipment are pooled

net cash provided by operating activities was $ 451.1 million . see `` item 7. md & a—liquidity and capital resources . '' current events as the novel coronavirus ( covid-19 ) continues to spread and significantly impact the united states , public and private sector policies and initiatives intended to reduce the transmission of covid-19 ( `` initiatives '' ) , such as the imposition of travel restrictions , mandates from federal , state and local authorities to avoid large gatherings of people , quarantine or `` shelter-in-place , '' the promotion of social distancing and the adoption of work-from-home and online learning by companies and institutions , could impact our operations . among other things , covid-19 and the initiatives could ( 1 ) adversely affect the ability of our suppliers , vendors and the manager to provide products and services to us , ( 2 ) result in decreased demand for our sites , and ( 3 ) make it more difficult for us and the manager to serve our customers , including as a result of delays or suspensions in the issuance of permits or other authorizations needed to conduct our business . due to the speed with which the situation is developing and factors beyond our knowledge or control , including the duration and severity of covid-19 and the initiatives as well as third-party actions taken to contain its spread and mitigate its public health effects , at this time we can not estimate or predict the impact of covid-19 or the initiatives on our business , financial position , results of operations or cash flows , particularly over the near to medium term , but the impact could be material . regulation s-x considerations in prior annual reports on form 10-k , ccl has included ( i ) audited financial statements of certain of ccl 's wholly owned subsidiaries whose securities are pledged as collateral for the 3.849 % secured notes that were required to be included therein pursuant to rule 3-16 of regulation s-x and ( ii ) certain other information in the notes to our audited consolidated financial statements with respect to ccl 's wholly owned subsidiaries that guarantee the 3.849 % secured notes pursuant to rule 3-10 of regulation s-x .


 Write a concise suspicious activity report of the following text delimited by triple backquotes. Return your response as a formal report which covers the key points highlighting the location,dates,entity names and account holder information in chronological order of the text.
     ```net cash provided by operating activities was $ 451.1 million . see `` item 7. md & a—liquidity and capital resources . '' current events as the novel coronavirus ( covid-19 ) continues to spread and significantly impact the united states , public and private sector policies and initiatives intended to reduce the transmission of covid-19 ( `` initiatives '' ) , such as the imposition of travel restrictions , mandates from federal , state and local authorities to avoid large gatherings of people , quarantine or `` shelter-in-place , '' the promotion of social distancing and the adoption of work-from-home and online learning by companies and institutions , could impact our operations . among other things , covid-19 and the initiatives could ( 1 ) adversely affect the ability of our suppliers , vendors and the manager to provide products and services to us , ( 2 ) result in decreased demand for our sites , and ( 3 ) make it more difficult for us and the manager to serve our customers , including as a result of delays or suspensions in the issuance of permits or other authorizations needed to conduct our business . due to the speed with which the situation is developing and factors beyond our knowledge or control , including the duration and severity of covid-19 and the initiatives as well as third-party actions taken to contain its spread and mitigate its public health effects , at this time we can not estimate or predict the impact of covid-19 or the initiatives on our business , financial position , results of operations or cash flows , particularly over the near to medium term , but the impact could be material . regulation s-x considerations in prior annual reports on form 10-k , ccl has included ( i ) audited financial statements of certain of ccl 's wholly owned subsidiaries whose securities are pledged as collateral for the 3.849 % secured notes that were required to be included therein pursuant to rule 3-16 of regulation s-x and ( ii ) certain other information in the notes to our audited consolidated financial statements with respect to ccl 's wholly owned subsidiaries that guarantee the 3.849 % secured notes pursuant to rule 3-10 of regulation s-x .
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 Suspicious Activity Report : a summary of our capital expenditures for the last three years is as follows : replace_table_token_4_th ( a ) includes capital expenditures recorded as a result of certain ccic transactions that result in permanent improvements to our towers . we are not a party to such transactions , and do not make cash payments in connection with such transactions . capital expenditures increased by approximately $ 15.7 million from 2018 to 2019 predominately due to a higher volume of improvements performed on existing sites . 18 financing activities the net cash flows used for financing activities during the years ended december 31 , 2019 and 2018 were impacted by our continued practice of distributing excess cash to our member . see note 7 to our consolidated financial statements . contractual cash obligations the following table summarizes our contractual cash obligations as of december 31 , 2019 . these contractual cash obligations relate primarily to our 3.849 % secured notes and lease obligations for land interests under our towers . replace_table_token_5_th ( a ) the following items are in addition to the obligations disclosed in the above table : we have a legal obligation to perform certain asset retirement activities , including requirements upon lease and easement terminations to remove sites or remediate the land upon which our site resides . the cash obligations disclosed in the above table , as of december 31 , 2019 , are exclusive of estimated undiscounted future cash outlays for asset retirement obligations of approximately $ 82.6 million . as of december 31 , 2019 , the net present value of these asset retirement obligations was approximately $ 11.4 million . see note 10 to our consolidated financial statements . we are contractually obligated to pay or reimburse others for property taxes related to our sites . ccic has the option to purchase approximately 68 % of our sites that are leased or subleased or operated and managed under sprint master leases at the end of their contract term . ccic has no obligation to exercise the purchase option . see note 1 to our consolidated financial statements . we have legal obligations for open purchase order commitments obtained in the ordinary course of business that have not yet been fulfilled . ( b ) amounts relate primarily to lease obligations for the land interests on which our towers reside and are based on the assumption that payments will be made for certain renewal periods exercisable at our option that are reasonably certain to be exercised and excludes our contingent payments for operating leases ( such as payments based on revenues derived from sites located on the leased asset ) as such arrangements are excluded from our operating lease liability . see note 11 to our consolidated financial statements for a further discussion of our operating lease obligations . debt restrictions the secured notes indenture does not contain financial maintenance covenants but it does contain restrictive covenants , subject to certain exceptions , related to our ability to incur indebtedness , incur liens , enter into certain mergers or change of control transactions , sell or issue equity interests , and enter into related party transactions . with respect to the restriction regarding the issuance of debt , we may not issue debt other than ( 1 ) certain permitted refinancings of the 3.849 % secured notes , ( 2 ) unsecured trade payables in the ordinary course of business and financing of equipment , land or other property up to an aggregate of $ 100.0 million or ( 3 ) unsecured debt or additional notes under the secured notes indenture provided that the debt to adjusted consolidated cash flow ratio ( as defined in the secured notes indenture ) at the time of incurrence , and after giving effect to such incurrence , would have been no greater than 3.5 to 1. as of december 31 , 2019 , our debt to adjusted consolidated cash flow ratio was 2.3 to 1 , and , as a result , we are currently not restricted in our ability to incur additional indebtedness . for purposes of restrictions related to our secured notes indenture , relevant debt calculations ( such as our debt to adjusted consolidated cash flow ratio ) are calculated in accordance with gaap that was in effect as of december 2012 , and , as such , exclude the impact of our lease liability recorded as a result of our new lease standard adoption on january 1 , 2019. further , we are not restricted in our ability to distribute cash to affiliates or issue dividends to our member . accounting and reporting matters critical accounting policies and estimates our critical accounting policies and estimates are those that we believe ( 1 ) are most important to the portrayal of our financial condition and results of operations or ( 2 ) require our most difficult , subjective or complex judgments , often as a result of the need to make estimates about the effect of matters that are inherently uncertain . in many cases , the accounting treatment of a particular transaction is specifically prescribed by gaap . in other cases , management is required to exercise judgment in the application of accounting principles with respect to particular transactions . the critical accounting policies and estimates for 2019 are not intended to be a comprehensive list of our accounting policies and estimates . see note 3 to our consolidated financial statements for a summary of our significant accounting policies , including information related to our adoption of the new lease accounting guidance ( commonly referred to as `` acs 842 `` or `` new lease standard `` on january 1 , 2019 . 19 lease accounting - lessee . our lessee arrangements primarily consist of ground leases for land under our towers . story_separator_special_tag any purchase price in excess of the net fair value of the assets acquired and liabilities assumed is allocated to goodwill . the fair value of the vast majority of our assets and liabilities is determined by using either : 20 ( 1 ) estimates of replacement costs ( for tangible fixed assets such as sites ) , or ( 2 ) discounted cash flow valuation methods ( for estimating identifiable intangibles such as site rental contracts and tenant relationships or operating lease right-of-use assets and lease liabilities acquired ) . the purchase price allocation requires subjective estimates that , if incorrectly estimated , could be material to our consolidated financial statements , including the amount of depreciation , amortization and accretion expense . the most important estimates for measurement of tangible fixed assets are : ( 1 ) the cost to replace the asset with a new asset and ( 2 ) the economic useful life after giving effect to age , quality and condition . the most important estimates for measurement of intangible assets are ( 1 ) discount rates and ( 2 ) timing , length and amount of cash flows including estimates regarding tenant renewals and cancellations . the most important estimates for measurement of operating lease rou assets and lease liabilities acquired are ( 1 ) present value of our future lease payments , including whether renewals or extensions should be measured , and ( 2 ) favorability or unfavorability to the current market terms . we record the fair value of obligations to perform certain asset retirement activities , including requirements , pursuant to our ground contracts or easements , to remove sites or remediate the land upon which certain of our sites reside . in determining the fair value of these asset retirement obligations , we must make several subjective and highly judgmental estimates such as those related to : ( 1 ) timing of cash flows , ( 2 ) future costs , ( 3 ) discount rates and ( 4 ) the probability of enforcement to remove the towers or remediate the land . see note 3 to our consolidated financial statements . accounting for long-lived assets — useful lives . we are required to make subjective assessments as to the useful lives of our tangible and intangible assets for purposes of determining depreciation , amortization and accretion expense that , if incorrectly estimated , could be material to our consolidated financial statements . depreciation expense for our property and equipment is computed using the straight-line method over the estimated useful lives of our various classes of tangible assets . the substantial portion of our property and equipment represents the cost of our sites , which is depreciated with an estimated useful life equal to the shorter of ( 1 ) 20 years or ( 2 ) the term of the lease ( including optional renewals ) for the land interests under the towers . the useful life of our intangible assets is estimated based on the period over which the intangible asset is expected to benefit us and gives consideration to the expected useful life of other assets to which the useful life may relate . we review the expected useful lives of our intangible assets on an ongoing basis and adjust if necessary . amortization expense for intangible assets is computed using the straight-line method over the estimated useful life of each of the intangible assets . the useful life of the site rental contracts and tenant relationships intangible assets is limited by the maximum depreciable life of the site ( 20 years ) , as a result of the interdependency of the sites and site rental contracts and tenant relationships . in contrast , the site rental contracts and tenant relationships are estimated to provide economic benefits for several decades because of the low rate of tenant cancellations and high rate of renewals experienced to date . thus , while site rental contracts and tenant relationships are valued based upon the fair value of the site rental contracts and tenant relationships which includes assumptions regarding both ( 1 ) tenants ' exercise of optional renewals contained in the acquired leases and ( 2 ) renewals of the acquired leases past the contractual term including exercisable options , the site rental contracts are amortized over a period not to exceed 20 years as a result of the useful life being limited by the depreciable life of the sites . accounting for long-lived assets — impairment evaluation . we review the carrying values of property and equipment , intangible assets or other long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amounts may not be recoverable . we utilize the following dual grouping policy for purposes of determining the unit of account for testing impairment of the site rental contracts and tenant relationships : ( 1 ) we pool site rental contracts and tenant relationships intangible assets and property and equipment into portfolio groups ; and ( 2 ) we separately pool site rental contracts and tenant relationships by significant tenant or by tenant grouping for individually insignificant tenants , as appropriate . we first pool site rental contracts and tenant relationships intangible assets and property and equipment into portfolio groups for purposes of determining the unit of account for impairment testing , because we view sites as portfolios and sites in a given portfolio and its related tenant contracts are not largely independent of the other sites in the portfolio . we re-evaluate the appropriateness of the pooled groups at least annually . this use of grouping is based in part on ( 1 ) our limitations regarding disposal of sites , ( 2 ) the interdependencies of site portfolios and ( 3 ) the manner in which sites are traded in the marketplace . the vast majority of our site rental contracts and tenant relationships intangible assets and property and equipment are pooled

