27.5: Percentage of U.S. federal government revenue from corporate income taxes, 1950-59

21.3: Percentage, 1960-69

15: Percentage, 1970-79

9.3: Percentage, 1980-89

10.5: Percentage, 1990-99

9.6: Estimated percentage, 2000-09

Source: U.S. Office of Management and Budget