Historical returns. Calculate the arithmetic average return of U.S. Treasury bills, long-term government bonds, and large-company stocks for 1988 to 1997. Which had the highest return? Which had the lowest return? On the left side, click on the Spreadsheet Learning Aid to see Table 8.1Year-by-Year Returns, 1950-1999. Historical returns. Calculate the arithmetic average return of U.S. Treasury bills, long-term government bonds, and large-company stocks for 1988 to 1997. Which had the highest return? Which had the lowest return? On the left side, click on the Spreadsheet Learning Aid to see Table 8.1Year-by-Year Returns, 1950-1999