Calculate the times interest earned ratio for each year end.

Dec. 31, 2020 $ 85,965 Dec. 31, 2019 $ 70,697 Dec. 31, 2018 $ 55,838 Revenue Costs and expenses: Cost of revenue Research and development Marketing and sales General and administrative Total costs and expenses Income from operations Interest and other income, net Income before provision for income taxes Provision for income taxes Net income Less: Net income attributable to participating securities Net income attributable to Class A and Class B common stockholders 16,692 18,447 11,591 6,564 53,294 32,671 509 33,180 4,034 29,146 0 $ 29,146 12,770 13,600 9,876 10,465 46,711 23,986 826 24,812 6,327 18,485 0 $ 18,485 9,355 10,273 7,846 3,451 30,925 24,913 448 25,361 3,249 22,112 (1) $ 22,111