31  / SERVICE EXCELLENCE ITEM 6.  SELECTED FINANCIAL DATA The following table presents as of, and for the years ended, December 31, selected financial data related to the Company’s financial results for the last five fiscal years. The selected financial data should be read in conjunction with Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations and Item 8. Financial Statements and Supplementary Data. For information regarding historical exchange rates, please see Impact of Foreign Exchange on Earnings in Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations. (in millions, except per share data, percentage and ratios) 2019 2018 2017 2016 2015 Financial Performance and Liquidity Total revenues $ 7,792 $ 7,316 $ 6,554 $ 6,232 $ 6,712 Operating income 3,124 2,831 2,519 2,411 2,618 Adjusted operating income (1) 3,124 2,831 2,468 2,411 2,550 Net income 2,440 1,951 2,405 1,599 1,352 Adjusted income (1) 2,290 2,080 1,666 1,549 1,625 Basic earnings per share ("EPS") 17.58 13.65 16.49 10.69 8.47 Diluted EPS 17.52 13.61 16.44 10.63 8.40 Adjusted diluted EPS (1) 16.44 14.51 11.39 10.29 10.10 Dividends declared per share 3.1400 2.5125 2.1875 1.8500 1.4000 Cash provided by operating activities 2,990 2,712 2,182 2,089 2,459 Cash used in investing activities (1,803 ) (1,458 ) (1,295 ) (1,069 ) (1,123 ) Cash used in financing activities (1,111) (1,542) (700) (1,493) (957) Free cash (1) 1,357 1,289 874 1,007 1,381 Financial Position Total assets (2) $ 22,367 $ 21,254 $ 20,135 $ 19,221 $ 19,637 Total long-term debt, including current portion 8,757 8,696 8,159 8,684 8,957 Total shareholders' equity 7,069 6,636 6,437 4,626 4,796 Financial Ratios Operating ratio (3) 59.9 % 61.3 % 61.6 % 61.3 % 61.0 % Adjusted operating ratio (1) 59.9% 61.3% 62.4% 61.3% 62.0% Return on invested capital ("ROIC") (1) 17.9 % 15.3 % 20.5 % 14.4 % 12.9 % Adjusted ROIC (1) 16.9% 16.2% 14.7% 14.0% 15.2% Dividend payout ratio (4) 17.9 % 18.5 % 13.3 % 17.4 % 16.7 % Adjusted dividend payout ratio (1) 19.1% 17.3% 19.2% 18.0% 13.9% Long-term debt to Net income ratio (5) 3.6 4.5 3.4 5.4 6.6 Adjusted net debt to adjusted EBITDA ratio (1) 2.4 2.6 2.6 2.9 2.8 $^{(1)}$ These measures have no standardized meanings prescribed by accounting principles generally accepted in the United States of America ("GAAP") and, therefore, may not be comparable to similar measures presented by other companies. These measures are defined and reconciled in Non-GAAP Measures in Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations. $^{(2)}$ Current period amount is as reported in compliance with GAAP following the adoption of Accounting Standards Update ("ASU") 2016-02 under the cumulative effect adjustment transition approach, discussed further in Item 8. Financial Statements and Supplementary Data, Note 2 Accounting changes. The comparative periods' amounts have not been restated and continue to be reported under the accounting standards in effect for those periods. $^{(3)}$ Operating ratio is defined as operating expenses divided by revenues. $^{(4)}$ Dividend payout ratio is defined as dividends declared per share divided by Diluted EPS. $^{(5)}$ Long-term debt to Net income ratio is defined as long-term debt, including long-term debt maturing within one year, divided by Net income.