Item 6. Selected Financial and Other Data
The following table sets forth selected historical consolidated financial data as of the dates and for the periods indicated. The selected consolidated statement of operations data for the years ended December 31, 2019, 2018 and 2017, and selected consolidated balance sheet data as of December 31, 2019 and 2018 have been derived from our audited consolidated financial statements and related notes appearing elsewhere in this Form 10-K. The selected consolidated statement of operations data for the years ended December 31, 2016 and 2015 and selected consolidated balance sheet data as of December 31, 2017, 2016 and 2015 have been derived from our audited consolidated financial statements, which are not included in this annual report on Form 10-K.
The results of operations for any period are not necessarily indicative of the results to be expected for any future period. The audited consolidated financial statements, from which the historical financial information for the periods set forth below have been derived, were prepared in accordance with U.S. generally accepted accounting principles (“GAAP”). The selected historical consolidated financial data set forth below should be read in conjunction with, and are qualified by reference to “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our audited consolidated financial statements and related notes thereto appearing elsewhere in this annual report on Form 10-K.
(1) Loss for the year ended December 31, 2019 included $1,004 million in impairment charges associated with our Connect reporting unit, a non-cash expense of $170 for the settlement of certain pension plans and $80 million in restructuring charges. See Item 7. “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Goodwill and Indefinite-Lived Intangible Asset”. See Note 11 “Pensions and Other Post-Retirement Benefits” for further discussion on the pension settlement charge.
(2) Loss for the year ended December 31, 2018 included $1,411 million in impairment charges associated with our Connect reporting unit and $139 million in restructuring charges. See Item 7. “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Goodwill and Indefinite- Lived Intangible Assets”.
(3) Income for the year ended December 31, 2017 included $80 million in restructuring charges.
(4) Income for the year ended December 31, 2016 included $105 million in restructuring charges.
(5) Income for the year ended December 31, 2015 included $51 million in restructuring charges, a gain of $158 million recorded from the step acquisition of Nielsen Catalina Solutions and an $8 million charge associated with the change to the Venezuelan currency exchange rate mechanism.
(6) Depreciation and amortization expense included charges for the depreciation and amortization of tangible and intangible assets acquired in business combinations of $205 million, $220 million, $219 million, $210 million and $205 million for the years ended December 31, 2019, 2018, 2017, 2016 and 2015, respectively.
Table:
(IN MILLIONS, EXCEPT PER SHARE AMOUNTS) | Year Ended December 31, |  |  |  | 
 | 2019(1) | 2018(2) | 2017(3) | 2016(4) | 2015(5)
Statement of Operations Data: |  |  |  |  | 
Revenues | $6,498 | $6,515 | $6,572 | $6,309 | $6,172
Depreciation and amortization(6) | 756 | 675 | 640 | 603 | 574
Operating income/(loss) | (93) | (475) | 1,214 | 1,130 | 1,098
Interest expense | 397 | 394 | 374 | 333 | 311
Income/(loss) from continuing operations | (403) | (700) | 440 | 507 | 575
Income/(loss) from continuing operations per common share (basic) | (1.17) | (2.00) | 1.20 | 1.40 | 1.55
Income/(loss) from continuing operations per common share (diluted) | (1.17) | (2.00) | 1.20 | 1.39 | 1.54
Cash dividends declared per common share | 1.11 | 1.39 | 1.33 | 1.21 | 1.09
 | December 31, |  |  |  | 
(IN MILLIONS) | 2019 | 2018 | 2017 | 2016 | 2015
Balance Sheet Data: |  |  |  |  | 
Total assets | $14,319 | $15,179 | $16,866 | $15,730 | $15,303
Long-term debt including finance leases | 8,309 | 8,387 | 8,441 | 7,926 | 7,338


Question: How many of the years have revenue above 6,500 million?
Answer: 2
Calculation: 2018 ## 2017