these conditions include short-term and long-term interest rates , inflation , money supply , political issues , legislative and regulatory changes , fluctuations in both debt and equity capital markets and broad trends in industry and finance , all of which are beyond our control . macroeconomic conditions that affect the economy and the economic outlook of the united states and the rest of the world could adversely affect our customers and vendors , which could adversely affect our results of operations and financial condition . growth and expansion activities . our future revenue growth will depend on our ability to maintain our existing revenue base while expanding and increasing utilization at our existing and developing prime campus locations . our existing prime campus locations currently encompass 11 colocation facilities with an aggregate of up to 4.4 million gsf of space and up to 455 mw of power . as of december 31 , 2018 , the utilization rates at these prime campuses , based on currently available cabinets , were approximately 91 % , 58 % , and 88 % at the core campus , the citadel campus , and the pyramid campus , respectively . additionally , each of our existing primes has room for switch , inc. | 2018 form 10-k | 54 further expansion , and we have designs to add up to 5.9 million gsf of additional space to the citadel campus and 940,000 gsf of additional space to the pyramid campus . we may be unable to attract customers to our data centers or retain them for a number of reasons , including if we fail to provide competitive pricing terms , provide space that is deemed to be inferior to that of our competitors or are unable to provide services that our existing and potential customers desire . cost of power . we are a large consumer of power , and power costs account for a significant portion of our cost of revenue . we require power supply to provide many services we offer , such as powering and cooling our customers ' it equipment and operating critical data center plant and equipment infrastructure . pursuant to our service agreements , we provide our customers with a committed level of power supply availability and we have committed to operating our data centers with 100 % clean and renewable energy . most of our customer agreements provide the ability to increase our cost of service in response to an increase in the cost of energy ; however , our gross profit can be adversely affected by increases in our cost of energy if we choose not to pass along the increases to our customers . for instance , the seasonal increase in energy costs during the summer months has not historically resulted in an adjustment to our customer pricing , and therefore has resulted in a decrease in our gross profit in those periods . nonetheless , since becoming an unbundled purchaser of energy in nevada , we are able to purchase power in the open market through long-term power contracts , which we believe can subsequently reduce variability of power costs . additionally , our existing customers may not renew their contracts with us or may reduce the services purchased from us , or we may be unable to attract new customers , if we experience increased power costs or limited availability of power resources , including clean and renewable energy . our brand or reputation could be adversely affected if we are unable to operate our data centers with 100 % clean and renewable energy . capital expenditures . our growth and expansion initiatives require significant capital . the costs of constructing , developing , operating and maintaining data centers and growing our operations are substantial . while we strive to match the growth of our facilities to the demand for services , we still must spend significant amounts before we receive any revenue . if we are unable to generate sufficient capital to meet our anticipated capital requirements , our growth could slow and operations could be adversely affected . our maintenance capital expenditures were $ 8.0 million for the year ended december 31 , 2018 . growth in customers . our results of operations could be significantly affected by the growth or reduction of our customer base . we have over 850 customers , including some of the world 's largest technology and digital media companies , cloud and managed service providers , financial institutions and telecommunications providers . we believe we have significant opportunities to both grow penetration of our existing customers as well as attract new customers . our ability to attract new customers depends on a number of factors , including our ability to offer high quality services at competitive prices and the capability of our marketing and sales team to attract new customers . additionally , a significant portion of our revenue is highly dependent on our top 10 customers and the loss of these customers or any significant decrease in their business could adversely affect our results of operations . key metrics and non-gaap financial measures we monitor the following unaudited key metrics and financial measures that are not calculated in accordance with accounting principles generally accepted in the united states of america , or gaap , to help us evaluate our business , identify trends affecting our business , formulate business plans and make strategic decisions . replace_table_token_3_th recurring revenue we calculate recurring revenue as contractual revenue under signed contracts calculated in accordance with gaap for the applicable period . recurring revenue does not include any installation or other one-time revenue , which would be classified as non-recurring revenue . management uses recurring revenue as a supplemental performance measure because it provides a useful measure of increases or decreases in contractual revenue from our customers and provides a baseline revenue measure on which to plan expenses . story_separator_special_tag no impact fee expense was incurred for the year ended december 31 , 2018 . switch , inc. | 2018 form 10-k | 61 other income ( expense ) replace_table_token_11_th interest expense interest expense increased by $ 1.3 million , or 5 % , for the year ended december 31 , 2018 , compared to the year ended december 31 , 2017 . the increase was driven primarily by an increase in our weighted average interest rate from 3.73 % for the year ended december 31 , 2017 to 4.23 % for the year ended december 31 , 2018 , related to our libor-based borrowings . in addition , during the year ended december 31 , 2018 , we corrected an immaterial amount of $ 0.4 million in additional interest expense that should have been expensed during the periods from june 30 , 2017 through december 31 , 2017. for further information , see note 2 “ summary of significant accounting policies—prior period adjustments ” within our consolidated financial statements . equity in net losses of investments equity in net losses of investments related to our equity method investments in supernap international decreased by $ 0.7 million , or 69 % , for the year ended december 31 , 2018 , compared to the year ended december 31 , 2017 . the net losses for these periods are related to the financial performance of our equity method investment in supernap international . as the carrying value of our investment in supernap international was reduced to zero as a result of recording our share of its losses as of march 31 , 2018 , we discontinued the equity method of accounting and will not provide for additional losses until our share of future net income , if any , equals the share of net losses not recognized during the period the equity method was suspended . loss on extinguishment of debt loss on extinguishment of debt was $ 3.6 million for the year ended december 31 , 2017 related to the refinancing of our prior credit agreement in june 2017. there was no such extinguishment of debt during the year ended december 31 , 2018 . other other income increased by $ 2.0 million , or 146 % , for the year ended december 31 , 2018 , compared to the year ended december 31 , 2017 due to an increase in interest income earned on our cash equivalents . income tax ( expense ) benefit years ended december 31 , change 2018 2017 amount % ( dollars in thousands ) income tax ( expense ) benefit $ ( 1,943 ) $ 981 $ ( 2,924 ) nm nm - not meaningful during the year ended december 31 , 2018 , we incurred $ 1.9 million of income tax expense compared to $ 1.0 million of income tax benefit during the year ended december 31 , 2017 . the income tax expense and benefit are driven by our allocable share of switch , ltd. 's income and loss before income taxes , respectively . as a partnership , switch , ltd. is not subject to u.s. federal and certain state and local income taxes ; therefore , as the ipo and certain organizational transactions in connection with our ipo were not completed until october 2017 , there was no provision or benefit for income taxes for the period from january 1 , 2017 to october 10 , 2017. switch , inc. | 2018 form 10-k | 62 net income attributable to noncontrolling interest years ended december 31 , change 2018 2017 amount % ( dollars in thousands ) net income attributable to noncontrolling interest $ 25,266 $ 6,628 $ 18,638 281 % net income attributable to noncontrolling interest increased by $ 18.6 million , or 281 % for the year ended december 31 , 2018 , compared to the year ended december 31 , 2017 due to an increase in net income . comparison of the years ended december 31 , 2017 and 2016 revenue replace_table_token_12_th revenue increased by $ 59.9 million , or 19 % , for the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 . the increase was primarily attributable to increases of $ 45.7 million in colocation revenue and $ 14.0 million in connectivity revenue , both of which resulted from an increased volume of sales to existing customers along with the addition of new customers as we expanded the facilities in the core campus throughout 2016 and 2017 and opened the first facilities in the pyramid campus and the citadel campus in june 2016 and november 2016 , respectively . of the overall increase , 16 % was attributable to new customers initiating service after december 31 , 2016 , and the remaining 84 % was attributable to growth from existing customers . our revenue churn rate was 0.6 % and 1.1 % during the years ended december 31 , 2017 and 2016 , respectively . cost of revenue and gross margin replace_table_token_13_th cost of revenue increased by $ 29.4 million , or 17 % , for the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 . the increase was primarily attributable to increases of $ 20.9 million in depreciation and amortization costs , $ 2.9 million in connectivity costs and $ 1.4 million in facilities costs , such as maintenance costs , associated with increased occupancy from the buildout and expansion of the core campus , the citadel campus and the pyramid campus . in addition , salaries and related employee expenses increased by $ 4.6 million due to an increase in direct labor costs from an increase in headcount , partially offset by a decrease in rent expense of $ 0.5 million . gross margin improved by 60 basis points for the year ended december 31 , 2017 , compared to the year ended december 31 , 2016.

cash flows the following table summarizes our cash flows : replace_table_token_15_th cash flows from operating activities cash from operating activities is primarily generated from operating income from our colocation and connectivity services . net cash provided by operating activities for the year ended december 31 , 2018 was $ 178.3 million , compared to $ 145.1 million for the year ended december 31 , 2017 . the increase of $ 33.2 million was primarily due to the $ 27.0 million payment of the impact fee to become an unbundled purchaser of electric resources in nevada to power our nevada data center facilities in may 2017 and changes in our working capital accounts . net cash provided by operating activities for the year ended december 31 , 2017 was $ 145.1 million , compared to $ 166.1 million for the year ended december 31 , 2016 . the decrease of $ 21.0 million was primarily due to the $ 27.0 million payment of the impact fee to become an unbundled purchaser of electric resources in nevada to power our nevada data center facilities in may 2017 and changes in our working capital accounts . cash flows from investing activities during the year ended december 31 , 2018 , net cash used in investing activities was $ 278.1 million , primarily consisting of capital expenditures of $ 275.5 million related to the expansion of our data center facilities and purchases of portfolio energy credits of $ 2.6 million . during the year ended december 31 , 2017 , net cash used in investing activities was $ 402.5 million , primarily consisting of capital expenditures of $ 402.6 million related to the expansion of our data center facilities , partially offset by proceeds from sale of property and equipment of $ 0.1 million .


 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.
     ```cash flows the following table summarizes our cash flows : replace_table_token_15_th cash flows from operating activities cash from operating activities is primarily generated from operating income from our colocation and connectivity services . net cash provided by operating activities for the year ended december 31 , 2018 was $ 178.3 million , compared to $ 145.1 million for the year ended december 31 , 2017 . the increase of $ 33.2 million was primarily due to the $ 27.0 million payment of the impact fee to become an unbundled purchaser of electric resources in nevada to power our nevada data center facilities in may 2017 and changes in our working capital accounts . net cash provided by operating activities for the year ended december 31 , 2017 was $ 145.1 million , compared to $ 166.1 million for the year ended december 31 , 2016 . the decrease of $ 21.0 million was primarily due to the $ 27.0 million payment of the impact fee to become an unbundled purchaser of electric resources in nevada to power our nevada data center facilities in may 2017 and changes in our working capital accounts . cash flows from investing activities during the year ended december 31 , 2018 , net cash used in investing activities was $ 278.1 million , primarily consisting of capital expenditures of $ 275.5 million related to the expansion of our data center facilities and purchases of portfolio energy credits of $ 2.6 million . during the year ended december 31 , 2017 , net cash used in investing activities was $ 402.5 million , primarily consisting of capital expenditures of $ 402.6 million related to the expansion of our data center facilities , partially offset by proceeds from sale of property and equipment of $ 0.1 million .
```    
 Suspicious Activity Report : these conditions include short-term and long-term interest rates , inflation , money supply , political issues , legislative and regulatory changes , fluctuations in both debt and equity capital markets and broad trends in industry and finance , all of which are beyond our control . macroeconomic conditions that affect the economy and the economic outlook of the united states and the rest of the world could adversely affect our customers and vendors , which could adversely affect our results of operations and financial condition . growth and expansion activities . our future revenue growth will depend on our ability to maintain our existing revenue base while expanding and increasing utilization at our existing and developing prime campus locations . our existing prime campus locations currently encompass 11 colocation facilities with an aggregate of up to 4.4 million gsf of space and up to 455 mw of power . as of december 31 , 2018 , the utilization rates at these prime campuses , based on currently available cabinets , were approximately 91 % , 58 % , and 88 % at the core campus , the citadel campus , and the pyramid campus , respectively . additionally , each of our existing primes has room for switch , inc. | 2018 form 10-k | 54 further expansion , and we have designs to add up to 5.9 million gsf of additional space to the citadel campus and 940,000 gsf of additional space to the pyramid campus . we may be unable to attract customers to our data centers or retain them for a number of reasons , including if we fail to provide competitive pricing terms , provide space that is deemed to be inferior to that of our competitors or are unable to provide services that our existing and potential customers desire . cost of power . we are a large consumer of power , and power costs account for a significant portion of our cost of revenue . we require power supply to provide many services we offer , such as powering and cooling our customers ' it equipment and operating critical data center plant and equipment infrastructure . pursuant to our service agreements , we provide our customers with a committed level of power supply availability and we have committed to operating our data centers with 100 % clean and renewable energy . most of our customer agreements provide the ability to increase our cost of service in response to an increase in the cost of energy ; however , our gross profit can be adversely affected by increases in our cost of energy if we choose not to pass along the increases to our customers . for instance , the seasonal increase in energy costs during the summer months has not historically resulted in an adjustment to our customer pricing , and therefore has resulted in a decrease in our gross profit in those periods . nonetheless , since becoming an unbundled purchaser of energy in nevada , we are able to purchase power in the open market through long-term power contracts , which we believe can subsequently reduce variability of power costs . additionally , our existing customers may not renew their contracts with us or may reduce the services purchased from us , or we may be unable to attract new customers , if we experience increased power costs or limited availability of power resources , including clean and renewable energy . our brand or reputation could be adversely affected if we are unable to operate our data centers with 100 % clean and renewable energy . capital expenditures . our growth and expansion initiatives require significant capital . the costs of constructing , developing , operating and maintaining data centers and growing our operations are substantial . while we strive to match the growth of our facilities to the demand for services , we still must spend significant amounts before we receive any revenue . if we are unable to generate sufficient capital to meet our anticipated capital requirements , our growth could slow and operations could be adversely affected . our maintenance capital expenditures were $ 8.0 million for the year ended december 31 , 2018 . growth in customers . our results of operations could be significantly affected by the growth or reduction of our customer base . we have over 850 customers , including some of the world 's largest technology and digital media companies , cloud and managed service providers , financial institutions and telecommunications providers . we believe we have significant opportunities to both grow penetration of our existing customers as well as attract new customers . our ability to attract new customers depends on a number of factors , including our ability to offer high quality services at competitive prices and the capability of our marketing and sales team to attract new customers . additionally , a significant portion of our revenue is highly dependent on our top 10 customers and the loss of these customers or any significant decrease in their business could adversely affect our results of operations . key metrics and non-gaap financial measures we monitor the following unaudited key metrics and financial measures that are not calculated in accordance with accounting principles generally accepted in the united states of america , or gaap , to help us evaluate our business , identify trends affecting our business , formulate business plans and make strategic decisions . replace_table_token_3_th recurring revenue we calculate recurring revenue as contractual revenue under signed contracts calculated in accordance with gaap for the applicable period . recurring revenue does not include any installation or other one-time revenue , which would be classified as non-recurring revenue . management uses recurring revenue as a supplemental performance measure because it provides a useful measure of increases or decreases in contractual revenue from our customers and provides a baseline revenue measure on which to plan expenses . story_separator_special_tag no impact fee expense was incurred for the year ended december 31 , 2018 . switch , inc. | 2018 form 10-k | 61 other income ( expense ) replace_table_token_11_th interest expense interest expense increased by $ 1.3 million , or 5 % , for the year ended december 31 , 2018 , compared to the year ended december 31 , 2017 . the increase was driven primarily by an increase in our weighted average interest rate from 3.73 % for the year ended december 31 , 2017 to 4.23 % for the year ended december 31 , 2018 , related to our libor-based borrowings . in addition , during the year ended december 31 , 2018 , we corrected an immaterial amount of $ 0.4 million in additional interest expense that should have been expensed during the periods from june 30 , 2017 through december 31 , 2017. for further information , see note 2 “ summary of significant accounting policies—prior period adjustments ” within our consolidated financial statements . equity in net losses of investments equity in net losses of investments related to our equity method investments in supernap international decreased by $ 0.7 million , or 69 % , for the year ended december 31 , 2018 , compared to the year ended december 31 , 2017 . the net losses for these periods are related to the financial performance of our equity method investment in supernap international . as the carrying value of our investment in supernap international was reduced to zero as a result of recording our share of its losses as of march 31 , 2018 , we discontinued the equity method of accounting and will not provide for additional losses until our share of future net income , if any , equals the share of net losses not recognized during the period the equity method was suspended . loss on extinguishment of debt loss on extinguishment of debt was $ 3.6 million for the year ended december 31 , 2017 related to the refinancing of our prior credit agreement in june 2017. there was no such extinguishment of debt during the year ended december 31 , 2018 . other other income increased by $ 2.0 million , or 146 % , for the year ended december 31 , 2018 , compared to the year ended december 31 , 2017 due to an increase in interest income earned on our cash equivalents . income tax ( expense ) benefit years ended december 31 , change 2018 2017 amount % ( dollars in thousands ) income tax ( expense ) benefit $ ( 1,943 ) $ 981 $ ( 2,924 ) nm nm - not meaningful during the year ended december 31 , 2018 , we incurred $ 1.9 million of income tax expense compared to $ 1.0 million of income tax benefit during the year ended december 31 , 2017 . the income tax expense and benefit are driven by our allocable share of switch , ltd. 's income and loss before income taxes , respectively . as a partnership , switch , ltd. is not subject to u.s. federal and certain state and local income taxes ; therefore , as the ipo and certain organizational transactions in connection with our ipo were not completed until october 2017 , there was no provision or benefit for income taxes for the period from january 1 , 2017 to october 10 , 2017. switch , inc. | 2018 form 10-k | 62 net income attributable to noncontrolling interest years ended december 31 , change 2018 2017 amount % ( dollars in thousands ) net income attributable to noncontrolling interest $ 25,266 $ 6,628 $ 18,638 281 % net income attributable to noncontrolling interest increased by $ 18.6 million , or 281 % for the year ended december 31 , 2018 , compared to the year ended december 31 , 2017 due to an increase in net income . comparison of the years ended december 31 , 2017 and 2016 revenue replace_table_token_12_th revenue increased by $ 59.9 million , or 19 % , for the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 . the increase was primarily attributable to increases of $ 45.7 million in colocation revenue and $ 14.0 million in connectivity revenue , both of which resulted from an increased volume of sales to existing customers along with the addition of new customers as we expanded the facilities in the core campus throughout 2016 and 2017 and opened the first facilities in the pyramid campus and the citadel campus in june 2016 and november 2016 , respectively . of the overall increase , 16 % was attributable to new customers initiating service after december 31 , 2016 , and the remaining 84 % was attributable to growth from existing customers . our revenue churn rate was 0.6 % and 1.1 % during the years ended december 31 , 2017 and 2016 , respectively . cost of revenue and gross margin replace_table_token_13_th cost of revenue increased by $ 29.4 million , or 17 % , for the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 . the increase was primarily attributable to increases of $ 20.9 million in depreciation and amortization costs , $ 2.9 million in connectivity costs and $ 1.4 million in facilities costs , such as maintenance costs , associated with increased occupancy from the buildout and expansion of the core campus , the citadel campus and the pyramid campus . in addition , salaries and related employee expenses increased by $ 4.6 million due to an increase in direct labor costs from an increase in headcount , partially offset by a decrease in rent expense of $ 0.5 million . gross margin improved by 60 basis points for the year ended december 31 , 2017 , compared to the year ended december 31 , 2016.

