Year Percent 1950 30.89673 1955 28.22206 1960 25.48409 1965 25.51934 1970 25.35994 1975 27.46279 1980 30.76028 1985 33.65378 1990 32.88436 1995 28.95845 2000 24.37565 2005 24.26602 2010 22.06345 2015 22.46784 2020 24.13458 2025 25.36674 2030 25.73609 2035 25.41895 2040 24.96559 2045 24.59954 2050 24.61049 2055 24.18704 2060 23.569 2065 23.01593 2070 22.59283 2075 22.28635 2080 22.04881 2085 21.80773 2090 21.55843 2095 21.33849 2100 21.18499