we finance the purchase of aircraft and our business with available cash balances , internally generated funds , including through aircraft sales and trading activities and debt financings . our debt financing strategy is focused on raising unsecured debt in the global bank and debt capital markets , with a limited utilization of government guaranteed export credit or other forms of secured financing . in 2019 , we issued approximately $ 3.2 billion in senior unsecured notes bearing interest at fixed rates ranging from 2.25 % to 4.25 % with one note bearing interest at a floating rate of three-month libor plus 0.67 % , with maturities ranging from 2021 to 2029. in addition , we increased our unsecured revolving credit facility capacity to approximately $ 5.8 billion , representing a 27.9 % increase from 2018 and extended the final maturity date to may 5 , 2023 bearing interest at a floating rate of libor plus 1.05 % . we ended 2019 with total 49 debt outstanding , net of discounts and issuance costs , of $ 13.6 billion , of which 88.4 % was at a fixed rate and 96.6 % of which was unsecured . as of december 31 , 2019 , our composite cost of funds was 3.34 % . in 2019 , total revenues increased by 20.1 % to $ 2.0 billion , compared to 2018. the increase in our total revenues is primarily due to the $ 3.0 billion increase in the net book value of our operating lease portfolio and an increase in our aircraft sales , trading and other activity . during the year ended december 31 , 2019 , our net income available to common stockholders was $ 575.2 million compared to $ 510.8 million for the year ended december 31 , 2018. our diluted earnings per share for the full year 2019 was $ 5.09 compared to $ 4.60 for the full year 2018. the increase in net income available to common stockholders in 2019 as compared to 2018 was primarily due to the continued growth of our fleet and an increase in our aircraft sales , trading and other activity , partially offset by increases in our interest expense and selling , general and administrative expenses . our adjusted net income before income taxes excludes the effects of certain non-cash items , one-time or non-recurring items that are not expected to continue in the future and certain other items . our adjusted net income before income taxes for the year ended december 31 , 2019 was $ 781.2 million or $ 6.91 per diluted share , compared to $ 690.3 million , or $ 6.20 per diluted share for the year ended december 31 , 2018. the increase in our adjusted net income before income taxes was principally driven by the continued growth of our fleet and an increase in our aircraft sales , trading and other activity , partially offset by increases in our interest expense and selling , general and administrative expenses . adjusted net income before income taxes and adjusted diluted earnings per share before income taxes are measures of financial and operational performance that are not defined by u.s. generally accepted accounting principles ( “ gaap ” ) . see note 3 in “ item 6. selected financial data ” of this annual report on form 10-k for a discussion of adjusted net income before income taxes and adjusted diluted earnings per share before income taxes as non-gaap measures and a reconciliation of these measures to net income available to common stockholders . our fleet we have continued to build one of the world 's youngest operating lease portfolios , including some of the most fuel-efficient commercial jet transport aircraft . our fleet , based on net book value , increased by 19.1 % , to $ 18.7 billion as of december 31 , 2019 , compared to $ 15.7 billion as of december 31 , 2018. during the year ended december 31 , 2019 , we took delivery of 53 aircraft from our new order pipeline , purchased two incremental aircraft in the secondary market and sold 30 aircraft and transferred eight aircraft from our operating lease portfolio to flight equipment held for sale , which is included in other assets on the consolidated balance sheet , ending the year with a total of 292 aircraft in our operating lease portfolio . the weighted average fleet age and weighted average remaining lease term of our operating lease portfolio as of december 31 , 2019 were 3.5 years and 7.2 years , respectively . we also managed 83 aircraft as of december 31 , 2019 . ​ 50 portfolio metrics of our fleet as of december 31 , 2019 and 2018 are as follows : replace_table_token_13_th ( 1 ) weighted-average fleet age and remaining lease term calculated based on net book value of our operating lease portfolio . ( 2 ) as of december 31 , 2019 , we transferred eight aircraft to flight equipment held for sale which is included in other assets on the consolidated balance sheet . all of these aircraft are excluded from the owned fleet count and included in our managed fleet count . ( 3 ) as of december 31 , 2019 , we had options to acquire up to 45 boeing 737-8 max aircraft and up to 25 airbus a220 aircraft . as of december 31 , 2018 , we had options to acquire up to five airbus a350-1000 aircraft and 45 boeing 737-8 max aircraft . story_separator_special_tag these events of default are subject to a number of important exceptions and qualifications set forth in the purchase agreements . unsecured term financings from time to time , we enter into unsecured term facilities . during 2019 , we entered into three unsecured term facilities aggregating $ 205.0 million comprised of ( i ) a $ 80.0 million term facility with a term of one year and bearing interest at a floating rate of libor plus 1.00 % ; ( ii ) a $ 75.0 million term facility with a term of three years and bearing interest at a floating rate of three-month libor plus 1.00 % ; ( iii ) a $ 50.0 million term facility with a term of one year and bearing interest at a floating rate of libor plus 1.00 % . during 2019 , we also entered into agreements to increase ( a ) our $ 518.0 million term facility by $ 82.0 million to an aggregate principal amount of $ 600.0 million , with a term of four years and bearing interest at a floating rate of libor plus 1.125 % and ( b ) our $ 5.4 million term facility by $ 19.6 million to an aggregate principal amount of $ 25.0 million with the term of such facility extended four years and bearing interest at a fixed rate of 3.00 % . the outstanding balance on our unsecured term facilities as of december 31 , 2019 was $ 883.1 million , bearing interest at fixed rates ranging from 2.75 % to 3.50 % and five facilities bearing interest at floating rates ranging from libor plus 0.95 % to libor plus 1.125 % . as of december 31 , 2019 , the remaining maturities of all unsecured term facilities ranged from approximately 0.09 years to approximately 4.75 years . as of december 31 , 2018 , the outstanding balance on our unsecured term facilities was $ 607.3 million . unsecured revolving credit facilities we have a senior unsecured revolving credit facility governed by a second amended and restated credit agreement , dated may 5 , 2014 ( as amended , modified and supplemented thereafter ) , with jp morgan chase bank , n.a . , as administrative agent , and the lenders from time to time party thereto . as of december 31 , 2019 , the unsecured revolving credit facility provides us with financing capacity of up to $ 5.8 billion subject to the terms and conditions set forth therein . lenders hold revolving commitments totaling approximately $ 5.5 billion that mature on may 5 , 2023 , commitments totaling $ 245.0 million that mature on may 5 , 2022 , commitments totaling $ 5.0 million that mature on may 5 , 2021 , and commitments totaling $ 92.7 million that mature on may 5 , 2020. as of december 31 , 2019 , borrowings under the unsecured revolving credit facility will generally bear interest at either ( i ) libor plus a margin of 1.05 % per year or ( ii ) an alternative base rate plus a margin of 0.05 % per year , subject , in each case , to increases or decreases based on declines in the credit ratings for our debt . we are required to pay a facility fee of 0.20 % per year ( also subject to increases or decreases based on declines in the credit ratings for our debt ) in respect of total commitments under the unsecured revolving credit facility . borrowings under the unsecured revolving credit facility are used to finance our working capital needs in the ordinary course of business and for other general corporate purposes . the total amount outstanding under our unsecured revolving credit facility was $ 20.0 million and $ 602.0 million as of december 31 , 2019 and december 31 , 2018 , respectively . the unsecured revolving credit facility provides for certain covenants , including covenants that limit our subsidiaries ' ability to incur , create , or assume certain unsecured indebtedness , and our subsidiaries ' abilities to engage 58 in certain mergers , consolidations , and asset sales . the unsecured revolving credit facility also requires us to comply with certain financial maintenance covenants ( measured at the end of each fiscal quarter ) including a maximum consolidated leverage ratio , minimum consolidated shareholders ' equity , and minimum consolidated unencumbered assets , as well as an interest coverage test that will be suspended when the unsecured revolving credit facility or certain of our other indebtedness is rated investment grade ( as defined in the unsecured revolving credit facility ) . as of december 31 , 2019 , such investment grade rating as defined in the unsecured revolving credit facility was achieved . we believe , as of december 31 , 2019 , we were in compliance in all material respects with all covenants contained in our unsecured revolving credit facility . in addition , the unsecured revolving credit facility contains customary events of default . in the case of an event of default , the lenders may terminate the commitments under the unsecured revolving credit facility and require immediate repayment of all outstanding borrowings and the cash collateralization of all outstanding letters of credit . such termination and acceleration will occur automatically in the event of certain bankruptcy events . these provisions are subject to a number of important exceptions and qualifications set forth in the credit agreement governing the unsecured revolving credit facility . during the year ended december 31 , 2019 , we entered into an uncommitted unsecured revolving credit facility with a total borrowing capacity of $ 175.0 million and a maturity date of october 18 , 2020 , bearing interest at a rate of libor plus 0.75 % . as of december 31 , 2019 , there were no outstanding amounts related to the uncommitted unsecured revolving credit facility . in january 2020 , we entered into an

liquidity and capital resources overview we finance the purchase of aircraft and our business with available cash balances , internally generated funds , including through aircraft sales and trading activity , and debt financings . we have structured ourselves with the goal to maintain investment-grade credit metrics and our debt financing strategy has focused on funding our business on an unsecured basis . unsecured financing provides us with operational flexibility when selling or transitioning aircraft from one airline to another . we ended 2019 with total debt outstanding , net of discounts and issuance costs , of $ 13.6 billion compared to $ 11.5 billion in 2018. our unsecured debt outstanding increased to $ 13.3 billion as of december 31 , 2019 from $ 11.3 billion as of december 31 , 2018. our unsecured debt as a percentage of total debt increased to 96.6 % as of december 31 , 2019 from 96.5 % as of december 31 , 2018. we increased our cash flows from operations by 11.0 % or $ 138.4 million to $ 1.4 billion in 2019 , as compared to $ 1.3 billion in 2018. our cash flows from operations increased primarily because of the continued growth of our fleet . our cash flow used in investing activities was $ 3.8 billion for the year ended december 31 , 2019 , which resulted primarily from the purchase of aircraft , partially offset by proceeds from our aircraft sales and trading activity . our cash flow provided by financing activities was $ 2.5 billion for the year ended december 31 , 2019 , which resulted primarily from the net proceeds received from the issuance of our unsecured notes and the issuance of preferred stock in 2019 , partially offset by the repayment of outstanding debt . we ended 2019 with available liquidity of $ 6.3 billion which is comprised of unrestricted cash of $ 317.5 million and undrawn balances under our unsecured revolving credit facilities of $ 6.0 billion .


 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.
     ```liquidity and capital resources overview we finance the purchase of aircraft and our business with available cash balances , internally generated funds , including through aircraft sales and trading activity , and debt financings . we have structured ourselves with the goal to maintain investment-grade credit metrics and our debt financing strategy has focused on funding our business on an unsecured basis . unsecured financing provides us with operational flexibility when selling or transitioning aircraft from one airline to another . we ended 2019 with total debt outstanding , net of discounts and issuance costs , of $ 13.6 billion compared to $ 11.5 billion in 2018. our unsecured debt outstanding increased to $ 13.3 billion as of december 31 , 2019 from $ 11.3 billion as of december 31 , 2018. our unsecured debt as a percentage of total debt increased to 96.6 % as of december 31 , 2019 from 96.5 % as of december 31 , 2018. we increased our cash flows from operations by 11.0 % or $ 138.4 million to $ 1.4 billion in 2019 , as compared to $ 1.3 billion in 2018. our cash flows from operations increased primarily because of the continued growth of our fleet . our cash flow used in investing activities was $ 3.8 billion for the year ended december 31 , 2019 , which resulted primarily from the purchase of aircraft , partially offset by proceeds from our aircraft sales and trading activity . our cash flow provided by financing activities was $ 2.5 billion for the year ended december 31 , 2019 , which resulted primarily from the net proceeds received from the issuance of our unsecured notes and the issuance of preferred stock in 2019 , partially offset by the repayment of outstanding debt . we ended 2019 with available liquidity of $ 6.3 billion which is comprised of unrestricted cash of $ 317.5 million and undrawn balances under our unsecured revolving credit facilities of $ 6.0 billion .
```    
 Suspicious Activity Report : we finance the purchase of aircraft and our business with available cash balances , internally generated funds , including through aircraft sales and trading activities and debt financings . our debt financing strategy is focused on raising unsecured debt in the global bank and debt capital markets , with a limited utilization of government guaranteed export credit or other forms of secured financing . in 2019 , we issued approximately $ 3.2 billion in senior unsecured notes bearing interest at fixed rates ranging from 2.25 % to 4.25 % with one note bearing interest at a floating rate of three-month libor plus 0.67 % , with maturities ranging from 2021 to 2029. in addition , we increased our unsecured revolving credit facility capacity to approximately $ 5.8 billion , representing a 27.9 % increase from 2018 and extended the final maturity date to may 5 , 2023 bearing interest at a floating rate of libor plus 1.05 % . we ended 2019 with total 49 debt outstanding , net of discounts and issuance costs , of $ 13.6 billion , of which 88.4 % was at a fixed rate and 96.6 % of which was unsecured . as of december 31 , 2019 , our composite cost of funds was 3.34 % . in 2019 , total revenues increased by 20.1 % to $ 2.0 billion , compared to 2018. the increase in our total revenues is primarily due to the $ 3.0 billion increase in the net book value of our operating lease portfolio and an increase in our aircraft sales , trading and other activity . during the year ended december 31 , 2019 , our net income available to common stockholders was $ 575.2 million compared to $ 510.8 million for the year ended december 31 , 2018. our diluted earnings per share for the full year 2019 was $ 5.09 compared to $ 4.60 for the full year 2018. the increase in net income available to common stockholders in 2019 as compared to 2018 was primarily due to the continued growth of our fleet and an increase in our aircraft sales , trading and other activity , partially offset by increases in our interest expense and selling , general and administrative expenses . our adjusted net income before income taxes excludes the effects of certain non-cash items , one-time or non-recurring items that are not expected to continue in the future and certain other items . our adjusted net income before income taxes for the year ended december 31 , 2019 was $ 781.2 million or $ 6.91 per diluted share , compared to $ 690.3 million , or $ 6.20 per diluted share for the year ended december 31 , 2018. the increase in our adjusted net income before income taxes was principally driven by the continued growth of our fleet and an increase in our aircraft sales , trading and other activity , partially offset by increases in our interest expense and selling , general and administrative expenses . adjusted net income before income taxes and adjusted diluted earnings per share before income taxes are measures of financial and operational performance that are not defined by u.s. generally accepted accounting principles ( “ gaap ” ) . see note 3 in “ item 6. selected financial data ” of this annual report on form 10-k for a discussion of adjusted net income before income taxes and adjusted diluted earnings per share before income taxes as non-gaap measures and a reconciliation of these measures to net income available to common stockholders . our fleet we have continued to build one of the world 's youngest operating lease portfolios , including some of the most fuel-efficient commercial jet transport aircraft . our fleet , based on net book value , increased by 19.1 % , to $ 18.7 billion as of december 31 , 2019 , compared to $ 15.7 billion as of december 31 , 2018. during the year ended december 31 , 2019 , we took delivery of 53 aircraft from our new order pipeline , purchased two incremental aircraft in the secondary market and sold 30 aircraft and transferred eight aircraft from our operating lease portfolio to flight equipment held for sale , which is included in other assets on the consolidated balance sheet , ending the year with a total of 292 aircraft in our operating lease portfolio . the weighted average fleet age and weighted average remaining lease term of our operating lease portfolio as of december 31 , 2019 were 3.5 years and 7.2 years , respectively . we also managed 83 aircraft as of december 31 , 2019 . ​ 50 portfolio metrics of our fleet as of december 31 , 2019 and 2018 are as follows : replace_table_token_13_th ( 1 ) weighted-average fleet age and remaining lease term calculated based on net book value of our operating lease portfolio . ( 2 ) as of december 31 , 2019 , we transferred eight aircraft to flight equipment held for sale which is included in other assets on the consolidated balance sheet . all of these aircraft are excluded from the owned fleet count and included in our managed fleet count . ( 3 ) as of december 31 , 2019 , we had options to acquire up to 45 boeing 737-8 max aircraft and up to 25 airbus a220 aircraft . as of december 31 , 2018 , we had options to acquire up to five airbus a350-1000 aircraft and 45 boeing 737-8 max aircraft . story_separator_special_tag these events of default are subject to a number of important exceptions and qualifications set forth in the purchase agreements . unsecured term financings from time to time , we enter into unsecured term facilities . during 2019 , we entered into three unsecured term facilities aggregating $ 205.0 million comprised of ( i ) a $ 80.0 million term facility with a term of one year and bearing interest at a floating rate of libor plus 1.00 % ; ( ii ) a $ 75.0 million term facility with a term of three years and bearing interest at a floating rate of three-month libor plus 1.00 % ; ( iii ) a $ 50.0 million term facility with a term of one year and bearing interest at a floating rate of libor plus 1.00 % . during 2019 , we also entered into agreements to increase ( a ) our $ 518.0 million term facility by $ 82.0 million to an aggregate principal amount of $ 600.0 million , with a term of four years and bearing interest at a floating rate of libor plus 1.125 % and ( b ) our $ 5.4 million term facility by $ 19.6 million to an aggregate principal amount of $ 25.0 million with the term of such facility extended four years and bearing interest at a fixed rate of 3.00 % . the outstanding balance on our unsecured term facilities as of december 31 , 2019 was $ 883.1 million , bearing interest at fixed rates ranging from 2.75 % to 3.50 % and five facilities bearing interest at floating rates ranging from libor plus 0.95 % to libor plus 1.125 % . as of december 31 , 2019 , the remaining maturities of all unsecured term facilities ranged from approximately 0.09 years to approximately 4.75 years . as of december 31 , 2018 , the outstanding balance on our unsecured term facilities was $ 607.3 million . unsecured revolving credit facilities we have a senior unsecured revolving credit facility governed by a second amended and restated credit agreement , dated may 5 , 2014 ( as amended , modified and supplemented thereafter ) , with jp morgan chase bank , n.a . , as administrative agent , and the lenders from time to time party thereto . as of december 31 , 2019 , the unsecured revolving credit facility provides us with financing capacity of up to $ 5.8 billion subject to the terms and conditions set forth therein . lenders hold revolving commitments totaling approximately $ 5.5 billion that mature on may 5 , 2023 , commitments totaling $ 245.0 million that mature on may 5 , 2022 , commitments totaling $ 5.0 million that mature on may 5 , 2021 , and commitments totaling $ 92.7 million that mature on may 5 , 2020. as of december 31 , 2019 , borrowings under the unsecured revolving credit facility will generally bear interest at either ( i ) libor plus a margin of 1.05 % per year or ( ii ) an alternative base rate plus a margin of 0.05 % per year , subject , in each case , to increases or decreases based on declines in the credit ratings for our debt . we are required to pay a facility fee of 0.20 % per year ( also subject to increases or decreases based on declines in the credit ratings for our debt ) in respect of total commitments under the unsecured revolving credit facility . borrowings under the unsecured revolving credit facility are used to finance our working capital needs in the ordinary course of business and for other general corporate purposes . the total amount outstanding under our unsecured revolving credit facility was $ 20.0 million and $ 602.0 million as of december 31 , 2019 and december 31 , 2018 , respectively . the unsecured revolving credit facility provides for certain covenants , including covenants that limit our subsidiaries ' ability to incur , create , or assume certain unsecured indebtedness , and our subsidiaries ' abilities to engage 58 in certain mergers , consolidations , and asset sales . the unsecured revolving credit facility also requires us to comply with certain financial maintenance covenants ( measured at the end of each fiscal quarter ) including a maximum consolidated leverage ratio , minimum consolidated shareholders ' equity , and minimum consolidated unencumbered assets , as well as an interest coverage test that will be suspended when the unsecured revolving credit facility or certain of our other indebtedness is rated investment grade ( as defined in the unsecured revolving credit facility ) . as of december 31 , 2019 , such investment grade rating as defined in the unsecured revolving credit facility was achieved . we believe , as of december 31 , 2019 , we were in compliance in all material respects with all covenants contained in our unsecured revolving credit facility . in addition , the unsecured revolving credit facility contains customary events of default . in the case of an event of default , the lenders may terminate the commitments under the unsecured revolving credit facility and require immediate repayment of all outstanding borrowings and the cash collateralization of all outstanding letters of credit . such termination and acceleration will occur automatically in the event of certain bankruptcy events . these provisions are subject to a number of important exceptions and qualifications set forth in the credit agreement governing the unsecured revolving credit facility . during the year ended december 31 , 2019 , we entered into an uncommitted unsecured revolving credit facility with a total borrowing capacity of $ 175.0 million and a maturity date of october 18 , 2020 , bearing interest at a rate of libor plus 0.75 % . as of december 31 , 2019 , there were no outstanding amounts related to the uncommitted unsecured revolving credit facility . in january 2020 , we entered into an

