Historical returns. Calculate the arithmetic average return of U.S. Treasury bills, long-term government bonds, and large-company stocks for 1950 to 1959 , 1960 to 1969 , 1970 to 1979 , and 1980 to 1989. Which had the highest return? Which had the lowest return? Click on "Get more help" menu, then select "Spreadsheet" to see Table 8.1-Year-by-Year Returns, 1950-1999. What is the average return of U.S. Treasury bills for 1950 to 1959,1960 to 1969,1970 to 1979 , and 1980 to 1989? The average return of U.S. Treasury bills from 1950 to 1959 is \%. (Round to two decimal places.)