Year Percent 1950 29.57706 1955 27.82682 1960 25.58039 1965 25.82725 1970 25.80935 1975 28.01249 1980 31.28733 1985 34.0451 1990 33.09175 1995 29.79831 2000 25.0229 2005 24.10622 2010 22.50894 2015 22.6897 2020 23.37686 2025 23.81714 2030 23.77592 2035 23.40427 2040 23.1442 2045 22.98245 2050 23.15805 2055 22.95863 2060 22.54864 2065 22.17157 2070 21.89258 2075 21.69253 2080 21.52397 2085 21.32899 2090 21.10295 2095 20.89653 2100 20.74371