progress on our strategic initiatives established in 2015 has created a sustainable platform positioning us for the continued execution of transformational changes that will provide greater long-term value for our shareholders . summarized results of operations replace_table_token_10_th on december 22 , 2017 , the tax cuts and jobs act ( “ tax reform ” ) was signed into law . as a result of the enactment of this law , in 2017 , “ purchased services and rents ” included a $ 151 million benefit and “ income taxes ” included a $ 3,331 million benefit , which added $ 3,482 million to “ net income ” and $ 12.00 to “ diluted earnings per share . ” the 2017 operating ratio was favorably impacted by 1.5 percentage points . for more information on the impact of tax reform , see note 4. the following table adjusts our 2017 gaap financial results to exclude the effects of tax reform , specifically , the effects of remeasurement of net deferred tax liabilities related to the reduction of the federal tax rate from 35 % to 21 % ( the “ 2017 tax adjustments ” ) . we use these non-gaap financial measures internally and believe this information provides useful supplemental information to investors to facilitate making period-to-period comparisons by excluding the 2017 tax adjustments . while we believe that these non-gaap financial measures are useful in evaluating our business , this information should be considered as supplemental in nature and is not meant to be considered in isolation or as a substitute for the related financial information prepared in accordance with gaap . in addition , these non-gaap financial measures may not be the same as similar measures presented by other companies . k 18 reconciliation of non-gaap financial measures replace_table_token_11_th in the table below and the paragraph following , references to 2017 results and related comparisons use the adjusted , non-gaap results from the reconciliation in the table above . replace_table_token_12_th income from railway operations rose in both comparisons resulting from higher railway operating revenues that more than offset higher expenses . revenue growth of 9 % and 7 % in 2018 and 2017 , respectively , was tempered by increased adjusted operating expenses of 4 % in both periods . in addition to higher income from railway operations , net income and diluted earnings per share growth in 2018 also benefited from a lower effective tax rate , primarily due to the enactment of tax reform . finally , our share repurchase programs in both years resulted in diluted earnings per share growth that exceeded that of net income . k 19 detailed results of operations railway operating revenues the following tables present a three-year comparison of revenues , volumes ( units ) , and average revenue per unit by commodity group . replace_table_token_13_th replace_table_token_14_th replace_table_token_15_th k 20 revenues increased $ 907 million and $ 663 million in 2018 and 2017 , respectively , compared to the prior years . as reflected in the table below , higher 2018 revenues were the result of higher average revenue per unit , driven by pricing gains and higher fuel surcharge revenue , partially offset by the mix-related impacts of increased intermodal volume and decreased coal volume . in addition , overall volume also increased . the rise in 2017 was largely the result of increased volume , particularly in our coal and intermodal markets , coupled with pricing gains . the table below reflects the components of the revenue change by major commodity group . replace_table_token_16_th most of our contracts include negotiated fuel surcharges , typically tied to either on-highway diesel ( ohd ) or west texas intermediate crude oil . approximately 90 % of our revenue base is covered by these negotiated fuel surcharges , with almost 75 % tied to ohd . for both 2018 and 2017 , contracts tied to ohd accounted for about 90 % of our fuel surcharge revenue . revenues associated with fuel surcharges totaled $ 657 million , $ 359 million , and $ 236 million in 2018 , 2017 , and 2016 , respectively . merchandise revenues increased in both 2018 and 2017 compared with the prior years . in 2018 , revenues grew due to higher average revenue per unit , driven by pricing gains and higher fuel surcharge revenue , as well as higher volumes . volume gains in chemicals , agriculture , and paper , clay , and forest products were partially offset by declines in automotive and metals and construction traffic . revenue growth in 2017 was a result of higher average revenue per unit , the result of price improvements . volume was relatively flat compared to the prior year , as gains in the metals and construction group were offset by declines in automotive , agriculture , and chemicals traffic . for 2019 , merchandise revenues are expected to increase , primarily the result of pricing gains . chemicals revenues rose in 2018 compared to a modest increase in 2017. in 2018 the rise was the result of higher volume and higher average revenue per unit , due to pricing gains and higher fuel surcharge revenue . volumes grew due to increased shipments of crude oil , liquefied petroleum gas , and plastics , partially offset by a decrease in coal ash shipments . the increase in 2017 was due to higher average revenue per unit , a result of favorable mix and price improvements , which outweighed declines in volume . volume declines were the result of fewer shipments of crude oil from the bakken oil fields , lower shipments of coal ash , partially offset by an increase in shipments of plastics . story_separator_special_tag we review assumptions related to our defined benefit plans annually , and while changes are likely to occur in assumptions concerning retirement age , projected earnings , and mortality , they are not expected to have a material effect on our net pension expense or net pension liability in the future . the net pension liability is recorded at net present value using discount rates that are based on the current interest rate environment in light of the timing of expected benefit payments . we utilize analyses in which the projected annual cash flows from the pension and postretirement benefit plans are matched with yield curves based on an appropriate universe of high-quality corporate bonds . we use the results of the yield curve analyses to select the discount rates that match the payment streams of the benefits in these plans . properties and depreciation most of our assets are long-lived railway properties ( note 7 ) . as disclosed in note 1 , the primary depreciation method for our asset base is group life . see note 1 for a more detailed discussion of the assumptions and estimates in this area . depreciation expense for 2018 totaled $ 1.1 billion . our composite depreciation rates for 2018 are disclosed in note 7 ; a one year increase ( or decrease ) in the estimated average useful lives of depreciable assets would have resulted in an approximate $ 40 million decrease ( or increase ) to depreciation expense . k 28 personal injury casualties and other claims expense , included in “ materials and other ” in the consolidated statements of income , includes our accrual for personal injury liabilities . to aid in valuing our personal injury liability and determining the amount to accrue with respect to such claims during the year , we utilize studies prepared by an independent consulting actuarial firm . the actuarial firm studies our historical patterns of reserving for claims and subsequent settlements , taking into account relevant outside influences . we adjust the liability quarterly based upon our assessment and the results of the study . our estimate is subject to inherent limitation given the difficulty of predicting future events and as such the ultimate loss sustained may vary from the estimated liability recorded . for a more detailed discussion of the assumptions and estimates in accounting for personal injury see note 17. income taxes our net deferred tax liability totaled $ 6.5 billion at december 31 , 2018 ( note 4 ) . this liability is estimated based on the expected future tax consequences of items recognized in the financial statements . after application of the federal statutory tax rate to book income , judgment is required with respect to the timing and deductibility of expenses in our income tax returns . for state income and other taxes , judgment is also required with respect to the apportionment among the various jurisdictions . a valuation allowance is recorded if we expect that it is more likely than not that deferred tax assets will not be realized . we have a $ 50 million valuation allowance on $ 425 million of deferred tax assets as of december 31 , 2018 , reflecting the expectation that almost all of these assets will be realized . other matters labor agreements approximately 80 % of our railroad employees are covered by collective bargaining agreements with various labor unions . pursuant to the railway labor act , these agreements remain in effect until new agreements are reached , or until the bargaining procedures mandated by the railway labor act are completed . we largely bargain nationally in concert with other major railroads , represented by the national carriers conference committee . moratorium provisions in the labor agreements govern when the railroads and unions may propose changes to the agreements . the 2015 bargaining round is now complete with finalized agreements in place with all employees . all of the newly negotiated agreements have moratorium provisions that will reopen the agreements for negotiation beginning january 1 , 2020. market risks at december 31 , 2018 , we had no outstanding debt subject to interest rate fluctuations . market risk for fixed-rate debt is estimated as the potential increase in fair value resulting from a one percentage point decrease in interest rates as of december 31 , 2018 , and amounts to an increase of approximately $ 1.4 billion to the fair value of our debt at december 31 , 2018. we consider it unlikely that interest rate fluctuations applicable to these instruments will result in a material adverse effect on our financial position , results of operations , or liquidity . new accounting pronouncements for a detailed discussion of new accounting pronouncements , see note 1. k 29 inflation in preparing financial statements , gaap requires the use of historical cost that disregards the effects of inflation on the replacement cost of property . as a capital-intensive company , we have most of our capital invested in long-lived assets . the replacement cost of these assets , as well as the related depreciation expense , would be substantially greater than the amounts reported on the basis of historical cost . forward-looking statements certain statements in management 's discussion and analysis of financial condition and results of operations are “ forward-looking statements ” within the meaning of the “ safe harbor ” provisions of the private securities litigation reform act of 1995 , as amended . these statements relate to future events or our future financial performance and involve known and unknown risks , uncertainties , and other factors that may cause our actual results , levels of activity , performance , or our achievements or those of our industry to be materially different from those expressed or implied by any forward-looking statements . in some cases , forward-looking statements can be identified by terminology such as “ may , ” “ will , ” “ could , ”

cash used in investing activities was $ 1.7 billion in 2018 , compared with $ 1.5 billion in 2017 , and $ 1.8 billion in 2016 . in 2018 , higher property additions drove the increase . the decline in 2017 was a reflection of lower cash outflows for property additions and a drop in corporate-owned life insurance investments . capital spending and track and equipment statistics can be found within the “ railway property ” section of part i of this report on form 10-k. for 2019 , we expect capital spending to approximate 16 % to 18 % of revenues . cash used in financing activities was $ 2.3 billion in 2018 , compared with $ 2.0 billion in 2017 , and $ 1.3 billion in 2016 . both year-over-year comparisons reflect increased repurchases of common stock and higher debt repayments . in 2018 , the increase was also impacted by higher dividend payments , but tempered by increased proceeds from borrowings . in 2017 , lower proceeds from borrowings also contributed to the rise . share repurchases totaled $ 2.8 billion in 2018 , $ 1.0 billion in 2017 , and $ 803 million in 2016 for the purchase and retirement of 17.1 million ( including 7.0 million shares repurchased for $ 1.2 billion under the asr program , see note 15 ) , 8.2 million , and 9.2 million shares , respectively . as of december 31 , 2018 , 39.4 million shares remain authorized by our board of directors for repurchase .


 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 used in investing activities was $ 1.7 billion in 2018 , compared with $ 1.5 billion in 2017 , and $ 1.8 billion in 2016 . in 2018 , higher property additions drove the increase . the decline in 2017 was a reflection of lower cash outflows for property additions and a drop in corporate-owned life insurance investments . capital spending and track and equipment statistics can be found within the “ railway property ” section of part i of this report on form 10-k. for 2019 , we expect capital spending to approximate 16 % to 18 % of revenues . cash used in financing activities was $ 2.3 billion in 2018 , compared with $ 2.0 billion in 2017 , and $ 1.3 billion in 2016 . both year-over-year comparisons reflect increased repurchases of common stock and higher debt repayments . in 2018 , the increase was also impacted by higher dividend payments , but tempered by increased proceeds from borrowings . in 2017 , lower proceeds from borrowings also contributed to the rise . share repurchases totaled $ 2.8 billion in 2018 , $ 1.0 billion in 2017 , and $ 803 million in 2016 for the purchase and retirement of 17.1 million ( including 7.0 million shares repurchased for $ 1.2 billion under the asr program , see note 15 ) , 8.2 million , and 9.2 million shares , respectively . as of december 31 , 2018 , 39.4 million shares remain authorized by our board of directors for repurchase .
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 Suspicious Activity Report : progress on our strategic initiatives established in 2015 has created a sustainable platform positioning us for the continued execution of transformational changes that will provide greater long-term value for our shareholders . summarized results of operations replace_table_token_10_th on december 22 , 2017 , the tax cuts and jobs act ( “ tax reform ” ) was signed into law . as a result of the enactment of this law , in 2017 , “ purchased services and rents ” included a $ 151 million benefit and “ income taxes ” included a $ 3,331 million benefit , which added $ 3,482 million to “ net income ” and $ 12.00 to “ diluted earnings per share . ” the 2017 operating ratio was favorably impacted by 1.5 percentage points . for more information on the impact of tax reform , see note 4. the following table adjusts our 2017 gaap financial results to exclude the effects of tax reform , specifically , the effects of remeasurement of net deferred tax liabilities related to the reduction of the federal tax rate from 35 % to 21 % ( the “ 2017 tax adjustments ” ) . we use these non-gaap financial measures internally and believe this information provides useful supplemental information to investors to facilitate making period-to-period comparisons by excluding the 2017 tax adjustments . while we believe that these non-gaap financial measures are useful in evaluating our business , this information should be considered as supplemental in nature and is not meant to be considered in isolation or as a substitute for the related financial information prepared in accordance with gaap . in addition , these non-gaap financial measures may not be the same as similar measures presented by other companies . k 18 reconciliation of non-gaap financial measures replace_table_token_11_th in the table below and the paragraph following , references to 2017 results and related comparisons use the adjusted , non-gaap results from the reconciliation in the table above . replace_table_token_12_th income from railway operations rose in both comparisons resulting from higher railway operating revenues that more than offset higher expenses . revenue growth of 9 % and 7 % in 2018 and 2017 , respectively , was tempered by increased adjusted operating expenses of 4 % in both periods . in addition to higher income from railway operations , net income and diluted earnings per share growth in 2018 also benefited from a lower effective tax rate , primarily due to the enactment of tax reform . finally , our share repurchase programs in both years resulted in diluted earnings per share growth that exceeded that of net income . k 19 detailed results of operations railway operating revenues the following tables present a three-year comparison of revenues , volumes ( units ) , and average revenue per unit by commodity group . replace_table_token_13_th replace_table_token_14_th replace_table_token_15_th k 20 revenues increased $ 907 million and $ 663 million in 2018 and 2017 , respectively , compared to the prior years . as reflected in the table below , higher 2018 revenues were the result of higher average revenue per unit , driven by pricing gains and higher fuel surcharge revenue , partially offset by the mix-related impacts of increased intermodal volume and decreased coal volume . in addition , overall volume also increased . the rise in 2017 was largely the result of increased volume , particularly in our coal and intermodal markets , coupled with pricing gains . the table below reflects the components of the revenue change by major commodity group . replace_table_token_16_th most of our contracts include negotiated fuel surcharges , typically tied to either on-highway diesel ( ohd ) or west texas intermediate crude oil . approximately 90 % of our revenue base is covered by these negotiated fuel surcharges , with almost 75 % tied to ohd . for both 2018 and 2017 , contracts tied to ohd accounted for about 90 % of our fuel surcharge revenue . revenues associated with fuel surcharges totaled $ 657 million , $ 359 million , and $ 236 million in 2018 , 2017 , and 2016 , respectively . merchandise revenues increased in both 2018 and 2017 compared with the prior years . in 2018 , revenues grew due to higher average revenue per unit , driven by pricing gains and higher fuel surcharge revenue , as well as higher volumes . volume gains in chemicals , agriculture , and paper , clay , and forest products were partially offset by declines in automotive and metals and construction traffic . revenue growth in 2017 was a result of higher average revenue per unit , the result of price improvements . volume was relatively flat compared to the prior year , as gains in the metals and construction group were offset by declines in automotive , agriculture , and chemicals traffic . for 2019 , merchandise revenues are expected to increase , primarily the result of pricing gains . chemicals revenues rose in 2018 compared to a modest increase in 2017. in 2018 the rise was the result of higher volume and higher average revenue per unit , due to pricing gains and higher fuel surcharge revenue . volumes grew due to increased shipments of crude oil , liquefied petroleum gas , and plastics , partially offset by a decrease in coal ash shipments . the increase in 2017 was due to higher average revenue per unit , a result of favorable mix and price improvements , which outweighed declines in volume . volume declines were the result of fewer shipments of crude oil from the bakken oil fields , lower shipments of coal ash , partially offset by an increase in shipments of plastics . story_separator_special_tag we review assumptions related to our defined benefit plans annually , and while changes are likely to occur in assumptions concerning retirement age , projected earnings , and mortality , they are not expected to have a material effect on our net pension expense or net pension liability in the future . the net pension liability is recorded at net present value using discount rates that are based on the current interest rate environment in light of the timing of expected benefit payments . we utilize analyses in which the projected annual cash flows from the pension and postretirement benefit plans are matched with yield curves based on an appropriate universe of high-quality corporate bonds . we use the results of the yield curve analyses to select the discount rates that match the payment streams of the benefits in these plans . properties and depreciation most of our assets are long-lived railway properties ( note 7 ) . as disclosed in note 1 , the primary depreciation method for our asset base is group life . see note 1 for a more detailed discussion of the assumptions and estimates in this area . depreciation expense for 2018 totaled $ 1.1 billion . our composite depreciation rates for 2018 are disclosed in note 7 ; a one year increase ( or decrease ) in the estimated average useful lives of depreciable assets would have resulted in an approximate $ 40 million decrease ( or increase ) to depreciation expense . k 28 personal injury casualties and other claims expense , included in “ materials and other ” in the consolidated statements of income , includes our accrual for personal injury liabilities . to aid in valuing our personal injury liability and determining the amount to accrue with respect to such claims during the year , we utilize studies prepared by an independent consulting actuarial firm . the actuarial firm studies our historical patterns of reserving for claims and subsequent settlements , taking into account relevant outside influences . we adjust the liability quarterly based upon our assessment and the results of the study . our estimate is subject to inherent limitation given the difficulty of predicting future events and as such the ultimate loss sustained may vary from the estimated liability recorded . for a more detailed discussion of the assumptions and estimates in accounting for personal injury see note 17. income taxes our net deferred tax liability totaled $ 6.5 billion at december 31 , 2018 ( note 4 ) . this liability is estimated based on the expected future tax consequences of items recognized in the financial statements . after application of the federal statutory tax rate to book income , judgment is required with respect to the timing and deductibility of expenses in our income tax returns . for state income and other taxes , judgment is also required with respect to the apportionment among the various jurisdictions . a valuation allowance is recorded if we expect that it is more likely than not that deferred tax assets will not be realized . we have a $ 50 million valuation allowance on $ 425 million of deferred tax assets as of december 31 , 2018 , reflecting the expectation that almost all of these assets will be realized . other matters labor agreements approximately 80 % of our railroad employees are covered by collective bargaining agreements with various labor unions . pursuant to the railway labor act , these agreements remain in effect until new agreements are reached , or until the bargaining procedures mandated by the railway labor act are completed . we largely bargain nationally in concert with other major railroads , represented by the national carriers conference committee . moratorium provisions in the labor agreements govern when the railroads and unions may propose changes to the agreements . the 2015 bargaining round is now complete with finalized agreements in place with all employees . all of the newly negotiated agreements have moratorium provisions that will reopen the agreements for negotiation beginning january 1 , 2020. market risks at december 31 , 2018 , we had no outstanding debt subject to interest rate fluctuations . market risk for fixed-rate debt is estimated as the potential increase in fair value resulting from a one percentage point decrease in interest rates as of december 31 , 2018 , and amounts to an increase of approximately $ 1.4 billion to the fair value of our debt at december 31 , 2018. we consider it unlikely that interest rate fluctuations applicable to these instruments will result in a material adverse effect on our financial position , results of operations , or liquidity . new accounting pronouncements for a detailed discussion of new accounting pronouncements , see note 1. k 29 inflation in preparing financial statements , gaap requires the use of historical cost that disregards the effects of inflation on the replacement cost of property . as a capital-intensive company , we have most of our capital invested in long-lived assets . the replacement cost of these assets , as well as the related depreciation expense , would be substantially greater than the amounts reported on the basis of historical cost . forward-looking statements certain statements in management 's discussion and analysis of financial condition and results of operations are “ forward-looking statements ” within the meaning of the “ safe harbor ” provisions of the private securities litigation reform act of 1995 , as amended . these statements relate to future events or our future financial performance and involve known and unknown risks , uncertainties , and other factors that may cause our actual results , levels of activity , performance , or our achievements or those of our industry to be materially different from those expressed or implied by any forward-looking statements . in some cases , forward-looking statements can be identified by terminology such as “ may , ” “ will , ” “ could , ”

