The following selected consolidated financial data should be read in conjunction with the consolidated financial statements and the notes thereto in Item 8 of Part II, "Financial Statements and Supplementary Data," and the information contained in Item 7 of Part II, "Management's Discussion and Analysis of Financial Condition and Results of Operations "Historical results are not necessarily indicative of future results. Year Ended December 31, 2018 (in millions, except per share data) 2016 2017 (1) 2019 2020 Statements of Operations: Net sales Operating income Net income (loss) $ 135,987 5 177,866 S S 4,186 $ 4,106 S 232,887 $ 12,421 S 280,522 S 386,064 14,541 S 22,899 $ 2,3715 3,033 S 10,073 S 11,588 $ 21,331 Basic camnings per share (2) $ 5.01 $ 6325 20.68 5 23.46 S 42.64 Diluted carnings per share (2) S 4.90 $ 6.15 $ 20.14 $ 23.01 $ 41.83 Weighted-average shares used in computation of earnings per share Basic 474 480 487 494 500 Diluted 484 493 500 504 510 Statements of Cash Flows: Net cash provided by (used in) operating activities (3) $ 17,203 $ 18365 S 30,723 S 38,514 5 66,064 2016 2017 December 31, 2018 2019(4) 2020 Balance Sheets: Total assets Total long-term obligations 83,402 S 20,301 S 131,310 $ 45,718 S 162,648 S 225,248 S 50,708 S 75,376 $ 321,195 101,406 (1) We acquired Whole Foods Market on August 28, 2017. The results of Whole Foods Market have been included in our results of operation from the date of acquisition (2) For further discussion of earnings per share, see Item 8 of Part II, "Financial Statements and Supplementary Data-Note 1-Description of Business, Accounting Policies, and Supplemental Disclosures (3) As a result of the adoption of new accounting guidance, we retrospectively adjusted our consolidated statements of cash flows to add restricted cash to cash and cash equivalents, which restated cash provided by operating activities by $(69) million in 2016 and 2017. (4) As a result of the adoption of new accounting guidance on January 1, 2019, we recognized lease assets and liabilities for operating leases with terms of more than twelve months Prior period amounts were not adjusted and continue to be reported in accordance with our historic accounting policies