Year Percent 1950 31.54266 1955 32.01673 1960 31.25812 1965 29.73505 1970 27.92177 1975 27.00033 1980 27.91075 1985 29.61032 1990 31.18856 1995 32.96419 2000 33.77791 2005 33.32998 2010 30.95462 2015 25.92859 2020 22.11704 2025 20.81093 2030 21.30618 2035 21.61724 2040 21.7306 2045 21.02285 2050 19.81135 2055 19.38351 2060 19.61898 2065 20.34546 2070 21.07222 2075 21.38792 2080 21.20155 2085 20.76279 2090 20.45337 2095 20.44232 2100 20.62733