historically , multiple contractual relationships with major airlines have enabled us to reduce our reliance on any single major airline code and to enhance and stabilize operating results through a mix of fixed‑fee arrangements and our prorate flying arrangements . for the year ended december 31 , 2018 , contract flying revenue and prorate revenue represented approximately 84.3 % and 15.7 % , respectively , of our total f lying agreements revenue . on contract routes , the major airline partner controls scheduling , ticketing , pricing and seat inventories and we are compensated by the major airline partner at contracted rates based on completed block hours ( measured from takeoff to landing , including taxi time ) , flight departures and other operating measures . our financial and operating results for the years ended december 31 , 2016 , 2017 and 2018 , and our financial position as of december 31 , 2017 and 2018 contained in this report , include the financial results and position of expressjet for those respective periods . financial highlights we had total operating revenues of $ 3.2 billion for the year ended december 31 , 2018 , a 3.2 % increase , compared to total operating revenues of $ 3.1 billion for the year ended december 31 , 2017. we had a net income of $ 280.4 million , or $ 5.30 per diluted share , for the year ended december 31 , 2018 , compared to net income of $ 428.9 million , or $ 8.08 per diluted share , for the year ended december 31 , 2017. our results for 2017 included a $ 246.8 million benefit related to the revaluation of our net deferred tax liability and other tax liabilities in accordance with the tax cuts and jobs act that was enacted into law in december 2017. the significant items affecting our financial performance during the year ended december 31 , 2018 are outlined below : revenue the number of aircraft we have in scheduled service and the number of block hours we generate on our flights are primary drivers to our f lying agreements revenue under our fixed-fee arrangements . during 2018 , we had a net increase in the number of aircraft operating under fixed-fee agreements . as summarized under the fleet activity section below , from december 31 , 2017 to december 31 , 2018 , we removed 48 aircraft from service that were operating under less profitable flying contracts and added 49 aircraft to new or existing fixed-fee arrangements at improved economics . the number of aircraft available for scheduled service increased from 595 aircraft at december 31 , 2017 to 596 at december 31 , 2018. our completed block hours decreased 4.5 % primarily due to the timing of our fleet transition during 2018. the majority of the aircraft removed from service during 2018 were removed during the first half of the year , whereas the majority of the aircraft added into service were added during the second half of the year . despite the reduction in our block hour production since 2017 , our total f lying agreements revenue increased 3.2 % from 2017 to 2018 primarily due to higher compensation we earned on aircraft , including new aircraft added in 2018 , partially offset by a decrease in revenue associated with the aircraft removed from our fleet . operating expenses the increase in our operating expense from 2017 to 2018 of $ 13.0 million , or 0.5 % , was primarily related to increased compensation paid to our crews since december 31 , 2017 , an increase in our average fuel costs per gallon on our prorate flying arrangements and an increase in other operating expenses , including pilot recruitment and training costs . additional details regarding the increase in our operating expenses are described in the section of this report entitled “ results of operations . ” fleet activity the following table summarizes our fleet activity for 2018 : 29 replace_table_token_10_th during 2018 , we took delivery of 39 new e175 aircraft and five new crj900 aircraft and placed the aircraft into service under fixed-fee flying agreements . we removed 16 crj900 aircraft from service and returned the aircraft to the lessor . we also removed 20 crj700 aircraft from service during 2018 that we either returned to the lessor , are in the process of transitioning to another major airline partner , or are pursuing alternative uses of the aircraft , including , but not limited to , leasing the aircraft or related engines to third parties . the five crj200 aircraft added to service during 2018 were temporarily out of service at december 31 , 2017. we removed 12 erj145s from service and returned the aircraft to the lessor . critical accounting policies and estimates our significant accounting policies are summarized in note 1 to our consolidated financial statements included in item 8 of this report . critical accounting policies are those policies that are most important to the preparation of our consolidated financial statements and require management 's subjective and complex judgments due to the need to make estimates about the effect of matters that are inherently uncertain . our critical accounting policies relate to revenue recognition , aircraft maintenance , aircraft leases , impairment of long‑lived assets , stock‑based compensation expense and fair value as discussed below . the application of these accounting policies involves the exercise of judgment and the use of assumptions as to future uncertainties and , as a result , actual results will likely differ , and could differ materially , from such estimates . revenue recognition flying agreements and airport customer service and other revenues are recognized when service is provided . under our fixed-fee and prorate flying agreements with our major airline partners , revenue is considered earned when each flight is completed . story_separator_special_tag we recorded a $ 246.8 million benefit in 2017 related to the revaluation of its net federal , state and other deferred tax liabilities based on the tax effects of the tax cuts and jobs act of 2017 ( the “ tax act ” ) . we also recorded a $ 4.5 million and $ 5.4 million benefit in 2018 and 2017 , respectively , relating to asu 2016-09 which requires excess tax benefits and deficiencies to be recognized in the income tax provision during the period stock options are vested/exercised . net income . primarily due to the factors described above , we generated net income of $ 280.4 million , or $ 5.30 per diluted share , for the year ended december 31 , 2018 , compared to a net income of $ 428.9 million , or $ 8.08 per diluted share , for the year ended december 31 , 2017 . 35 2017 compared to 2016 operational statistics . the following table sets forth our major operational statistics and the associated percentages of change for the periods identified below . the decrease in block hours , departures and passengers carried during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to a net reduction in our operating fleet from 652 aircraft to 595 aircraft between december 31 , 2016 and december 31 , 2017. replace_table_token_16_th operating revenues the following table summarizes our operating revenue for the periods indicated ( dollar amounts in thousands ) : replace_table_token_17_th flying agreements revenue primarily consists of revenue earned on flights we operate under our capacity purchase agreements and prorate agreements with our major airline partners . airport customer service and other revenues primarily consist of revenue earned from providing airport counter , gate and ramp services . changes in our flying agreements revenue are summarized below ( dollar amounts in thousands ) . replace_table_token_18_th the increase in “ capacity purchase agreements revenue : flight operations ” of $ 12.6 million was primarily due to 21 e175 aircraft added to our fleet and improved economics on flying contract renewals , partially offset by a reduction in revenue from aircraft removed from unprofitable or less profitable flying contracts since 2016 . the increase in “ capacity purchase agreement revenue : aircraft lease ” of $ 70.1 million was primarily due to higher aircraft ownership costs . the decrease in prorate agreements revenue of $ 16.0 million was primarily due to a change in markets from prorate agreements to capacity purchase agreements with higher revenue yields during the year ended december 31 , 2017. the $ 8.7 million decrease in airport customer service and other revenues was primarily related to a decrease in the volume of airport service agreements since december 31 , 2016 . 36 individual expense components attributable to our operations are set forth in the following table ( dollar amounts in thousands ) . replace_table_token_19_th salaries , wages and benefits . the $ 13.4 million , or 1.1 % , decrease in salaries , wages and benefits during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to a decrease in direct labor costs resulting from a net reduction in our fleet size and related level of departures and block hours , which was partially offset by higher crew compensation costs resulting from labor agreements executed since 2016. aircraft maintenance , materials and repairs . the $ 10.2 million , or 1.8 % , increase in aircraft maintenance expense during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to an increase in the number of scheduled maintenance events and an increase in the percentage of our fleet that is under long-term power-by-the-hour maintenance agreements , including the additional 21 e175 aircraft added since december 31 , 2016 , which was partially offset by a decrease in other direct maintenance costs resulting from a reduced fleet size and departures since 2016. depreciation and amortization . the $ 7.8 million , or 2.7 % , increase in depreciation and amortization expense during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to the purchase of 21 additional e175 aircraft and related long-lived aircraft parts in 2017. additionally , we acquired 19 e175 aircraft in the fourth quarter of 2016 that only had a partial year of depreciation in 2016. aircraft rentals . the $ 46.8 million , or 17.8 % , decrease in aircraft rentals during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to a decrease in leased aircraft from 415 leased aircraft for the year ended to december 31 , 2016 , to 319 leased aircraft for the year ended december 31 , 2017. aircraft fuel . the $ 14.4 million , or 20.4 % , increase in fuel cost during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to an increase in our average fuel cost per gallon from $ 1.72 for the year ended december 31 , 2016 to $ 2.06 for the year ended december 31 , 2017. the following table summarizes the gallons of fuel we purchased under our prorate agreements , for the periods indicated : replace_table_token_20_th airport-related expenses . the $ 3.8 million , or 3.1 % , decrease in airport-related expenses during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to a reduction in passenger interruption related costs during the year ended december 31 , 2017 . 37 special items . special items for the year ended december 31 , 2016 included impairment charges and inventory

cash position and liquidity . the following table provides a summary of the net cash provided by ( used in ) our operating , investing and financing activities for the years ended december 31 , 2018 and 2017 , and our total cash and marketable securities position as of december 31 , 2018 and december 31 , 2017 ( in thousands ) . replace_table_token_23_th replace_table_token_24_th cash flows from operating activities . net cash provided by operating activities increased $ 118.4 million , or 17.3 % , during 2018 , compared to 2017 , primarily due to an increase in pre-tax income from 2018 to 2017 of $ 78.1 million and changes in our working capital accounts . cash flows from investing activities . net cash used in investing activities increased $ 232.1 million , or 30.9 % , during 2018 , compared to 2017 , primarily due to the acquisition of 39 e175 aircraft and the related spare aircraft assets during 2017 , compared to 21 e175 aircraft and the related spare aircraft assets purchased during 2017 , significantly offset by net liquidation of marketable securities , which provided an additional $ 236.2 million during 2018 compared to 2017. additionally , during 2017 we received proceeds from the sale of 15 crj200 aircraft , eleven emb120 aircraft , one crj700 aircraft and related spare aircraft assets for $ 52.0 million . cash flows from financing activities .


 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 position and liquidity . the following table provides a summary of the net cash provided by ( used in ) our operating , investing and financing activities for the years ended december 31 , 2018 and 2017 , and our total cash and marketable securities position as of december 31 , 2018 and december 31 , 2017 ( in thousands ) . replace_table_token_23_th replace_table_token_24_th cash flows from operating activities . net cash provided by operating activities increased $ 118.4 million , or 17.3 % , during 2018 , compared to 2017 , primarily due to an increase in pre-tax income from 2018 to 2017 of $ 78.1 million and changes in our working capital accounts . cash flows from investing activities . net cash used in investing activities increased $ 232.1 million , or 30.9 % , during 2018 , compared to 2017 , primarily due to the acquisition of 39 e175 aircraft and the related spare aircraft assets during 2017 , compared to 21 e175 aircraft and the related spare aircraft assets purchased during 2017 , significantly offset by net liquidation of marketable securities , which provided an additional $ 236.2 million during 2018 compared to 2017. additionally , during 2017 we received proceeds from the sale of 15 crj200 aircraft , eleven emb120 aircraft , one crj700 aircraft and related spare aircraft assets for $ 52.0 million . cash flows from financing activities .
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 Suspicious Activity Report : historically , multiple contractual relationships with major airlines have enabled us to reduce our reliance on any single major airline code and to enhance and stabilize operating results through a mix of fixed‑fee arrangements and our prorate flying arrangements . for the year ended december 31 , 2018 , contract flying revenue and prorate revenue represented approximately 84.3 % and 15.7 % , respectively , of our total f lying agreements revenue . on contract routes , the major airline partner controls scheduling , ticketing , pricing and seat inventories and we are compensated by the major airline partner at contracted rates based on completed block hours ( measured from takeoff to landing , including taxi time ) , flight departures and other operating measures . our financial and operating results for the years ended december 31 , 2016 , 2017 and 2018 , and our financial position as of december 31 , 2017 and 2018 contained in this report , include the financial results and position of expressjet for those respective periods . financial highlights we had total operating revenues of $ 3.2 billion for the year ended december 31 , 2018 , a 3.2 % increase , compared to total operating revenues of $ 3.1 billion for the year ended december 31 , 2017. we had a net income of $ 280.4 million , or $ 5.30 per diluted share , for the year ended december 31 , 2018 , compared to net income of $ 428.9 million , or $ 8.08 per diluted share , for the year ended december 31 , 2017. our results for 2017 included a $ 246.8 million benefit related to the revaluation of our net deferred tax liability and other tax liabilities in accordance with the tax cuts and jobs act that was enacted into law in december 2017. the significant items affecting our financial performance during the year ended december 31 , 2018 are outlined below : revenue the number of aircraft we have in scheduled service and the number of block hours we generate on our flights are primary drivers to our f lying agreements revenue under our fixed-fee arrangements . during 2018 , we had a net increase in the number of aircraft operating under fixed-fee agreements . as summarized under the fleet activity section below , from december 31 , 2017 to december 31 , 2018 , we removed 48 aircraft from service that were operating under less profitable flying contracts and added 49 aircraft to new or existing fixed-fee arrangements at improved economics . the number of aircraft available for scheduled service increased from 595 aircraft at december 31 , 2017 to 596 at december 31 , 2018. our completed block hours decreased 4.5 % primarily due to the timing of our fleet transition during 2018. the majority of the aircraft removed from service during 2018 were removed during the first half of the year , whereas the majority of the aircraft added into service were added during the second half of the year . despite the reduction in our block hour production since 2017 , our total f lying agreements revenue increased 3.2 % from 2017 to 2018 primarily due to higher compensation we earned on aircraft , including new aircraft added in 2018 , partially offset by a decrease in revenue associated with the aircraft removed from our fleet . operating expenses the increase in our operating expense from 2017 to 2018 of $ 13.0 million , or 0.5 % , was primarily related to increased compensation paid to our crews since december 31 , 2017 , an increase in our average fuel costs per gallon on our prorate flying arrangements and an increase in other operating expenses , including pilot recruitment and training costs . additional details regarding the increase in our operating expenses are described in the section of this report entitled “ results of operations . ” fleet activity the following table summarizes our fleet activity for 2018 : 29 replace_table_token_10_th during 2018 , we took delivery of 39 new e175 aircraft and five new crj900 aircraft and placed the aircraft into service under fixed-fee flying agreements . we removed 16 crj900 aircraft from service and returned the aircraft to the lessor . we also removed 20 crj700 aircraft from service during 2018 that we either returned to the lessor , are in the process of transitioning to another major airline partner , or are pursuing alternative uses of the aircraft , including , but not limited to , leasing the aircraft or related engines to third parties . the five crj200 aircraft added to service during 2018 were temporarily out of service at december 31 , 2017. we removed 12 erj145s from service and returned the aircraft to the lessor . critical accounting policies and estimates our significant accounting policies are summarized in note 1 to our consolidated financial statements included in item 8 of this report . critical accounting policies are those policies that are most important to the preparation of our consolidated financial statements and require management 's subjective and complex judgments due to the need to make estimates about the effect of matters that are inherently uncertain . our critical accounting policies relate to revenue recognition , aircraft maintenance , aircraft leases , impairment of long‑lived assets , stock‑based compensation expense and fair value as discussed below . the application of these accounting policies involves the exercise of judgment and the use of assumptions as to future uncertainties and , as a result , actual results will likely differ , and could differ materially , from such estimates . revenue recognition flying agreements and airport customer service and other revenues are recognized when service is provided . under our fixed-fee and prorate flying agreements with our major airline partners , revenue is considered earned when each flight is completed . story_separator_special_tag we recorded a $ 246.8 million benefit in 2017 related to the revaluation of its net federal , state and other deferred tax liabilities based on the tax effects of the tax cuts and jobs act of 2017 ( the “ tax act ” ) . we also recorded a $ 4.5 million and $ 5.4 million benefit in 2018 and 2017 , respectively , relating to asu 2016-09 which requires excess tax benefits and deficiencies to be recognized in the income tax provision during the period stock options are vested/exercised . net income . primarily due to the factors described above , we generated net income of $ 280.4 million , or $ 5.30 per diluted share , for the year ended december 31 , 2018 , compared to a net income of $ 428.9 million , or $ 8.08 per diluted share , for the year ended december 31 , 2017 . 35 2017 compared to 2016 operational statistics . the following table sets forth our major operational statistics and the associated percentages of change for the periods identified below . the decrease in block hours , departures and passengers carried during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to a net reduction in our operating fleet from 652 aircraft to 595 aircraft between december 31 , 2016 and december 31 , 2017. replace_table_token_16_th operating revenues the following table summarizes our operating revenue for the periods indicated ( dollar amounts in thousands ) : replace_table_token_17_th flying agreements revenue primarily consists of revenue earned on flights we operate under our capacity purchase agreements and prorate agreements with our major airline partners . airport customer service and other revenues primarily consist of revenue earned from providing airport counter , gate and ramp services . changes in our flying agreements revenue are summarized below ( dollar amounts in thousands ) . replace_table_token_18_th the increase in “ capacity purchase agreements revenue : flight operations ” of $ 12.6 million was primarily due to 21 e175 aircraft added to our fleet and improved economics on flying contract renewals , partially offset by a reduction in revenue from aircraft removed from unprofitable or less profitable flying contracts since 2016 . the increase in “ capacity purchase agreement revenue : aircraft lease ” of $ 70.1 million was primarily due to higher aircraft ownership costs . the decrease in prorate agreements revenue of $ 16.0 million was primarily due to a change in markets from prorate agreements to capacity purchase agreements with higher revenue yields during the year ended december 31 , 2017. the $ 8.7 million decrease in airport customer service and other revenues was primarily related to a decrease in the volume of airport service agreements since december 31 , 2016 . 36 individual expense components attributable to our operations are set forth in the following table ( dollar amounts in thousands ) . replace_table_token_19_th salaries , wages and benefits . the $ 13.4 million , or 1.1 % , decrease in salaries , wages and benefits during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to a decrease in direct labor costs resulting from a net reduction in our fleet size and related level of departures and block hours , which was partially offset by higher crew compensation costs resulting from labor agreements executed since 2016. aircraft maintenance , materials and repairs . the $ 10.2 million , or 1.8 % , increase in aircraft maintenance expense during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to an increase in the number of scheduled maintenance events and an increase in the percentage of our fleet that is under long-term power-by-the-hour maintenance agreements , including the additional 21 e175 aircraft added since december 31 , 2016 , which was partially offset by a decrease in other direct maintenance costs resulting from a reduced fleet size and departures since 2016. depreciation and amortization . the $ 7.8 million , or 2.7 % , increase in depreciation and amortization expense during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to the purchase of 21 additional e175 aircraft and related long-lived aircraft parts in 2017. additionally , we acquired 19 e175 aircraft in the fourth quarter of 2016 that only had a partial year of depreciation in 2016. aircraft rentals . the $ 46.8 million , or 17.8 % , decrease in aircraft rentals during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to a decrease in leased aircraft from 415 leased aircraft for the year ended to december 31 , 2016 , to 319 leased aircraft for the year ended december 31 , 2017. aircraft fuel . the $ 14.4 million , or 20.4 % , increase in fuel cost during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to an increase in our average fuel cost per gallon from $ 1.72 for the year ended december 31 , 2016 to $ 2.06 for the year ended december 31 , 2017. the following table summarizes the gallons of fuel we purchased under our prorate agreements , for the periods indicated : replace_table_token_20_th airport-related expenses . the $ 3.8 million , or 3.1 % , decrease in airport-related expenses during the year ended december 31 , 2017 , compared to the year ended december 31 , 2016 , was primarily due to a reduction in passenger interruption related costs during the year ended december 31 , 2017 . 37 special items . special items for the year ended december 31 , 2016 included impairment charges and inventory

