Year Percent 1950 15.89873 1955 15.6569 1960 15.49078 1965 15.26126 1970 14.91106 1975 14.53098 1980 14.24313 1985 14.26416 1990 14.51702 1995 15.97804 2000 17.15129 2005 18.16536 2010 19.07432 2015 19.87051 2020 20.51475 2025 21.70669 2030 23.10822 2035 24.19499 2040 24.92188 2045 25.03185 2050 24.98144 2055 25.31945 2060 25.722 2065 26.02835 2070 26.03971 2075 25.69294 2080 25.34934 2085 25.09389 2090 24.89746 2095 24.69309 2100 24.42917