Year Percent 1950 27.21369 1955 27.96474 1960 25.07345 1965 25.22448 1970 24.13084 1975 22.55281 1980 23.07284 1985 22.79553 1990 24.6684 1995 26.75838 2000 28.49465 2005 28.46902 2010 26.94736 2015 27.47165 2020 29.51137 2025 30.23002 2030 30.54893 2035 28.78814 2040 25.04659 2045 23.06962 2050 22.34942 2055 22.23062 2060 23.49493 2065 24.25996 2070 23.71649 2075 23.04315 2080 22.59351 2085 22.60503 2090 22.96738 2095 23.3252 2100 23.25291