Year Percent 1950 30.53993 1955 29.2273 1960 28.16272 1965 27.41252 1970 27.23093 1975 27.62034 1980 25.27804 1985 26.01417 1990 27.20502 1995 27.6281 2000 27.92828 2005 28.85065 2010 31.25948 2015 33.35093 2020 34.13649 2025 33.85823 2030 33.20873 2035 32.09751 2040 31.27637 2045 30.56147 2050 29.4193 2055 28.19826 2060 26.97739 2065 25.88915 2070 24.94749 2075 24.12384 2080 23.40104 2085 22.79094 2090 22.29741 2095 21.91387 2100 21.62633