Year Percent 1950 17.74067 1955 16.9484 1960 15.21148 1965 14.57627 1970 14.80178 1975 14.94692 1980 15.36496 1985 16.08479 1990 16.55031 1995 16.20181 2000 17.13814 2005 21.484 2010 24.28523 2015 23.05219 2020 23.87538 2025 25.01415 2030 26.52177 2035 28.79385 2040 29.85495 2045 29.05457 2050 26.46403 2055 23.92606 2060 22.19683 2065 22.14121 2070 23.56707 2075 24.13462 2080 23.98469 2085 22.86433 2090 21.69164 2095 21.34649 2100 21.79137