Year Percent 1950 23.88571 1955 28.03297 1960 31.65209 1965 32.59243 1970 29.54355 1975 31.03885 1980 32.16917 1985 34.46258 1990 32.87766 1995 31.69289 2000 29.19258 2005 28.89314 2010 28.83623 2015 28.85753 2020 28.44653 2025 27.26012 2030 26.69164 2035 25.74235 2040 24.85167 2045 24.07194 2050 23.05212 2055 22.29144 2060 21.79147 2065 21.46998 2070 21.2253 2075 21.02769 2080 20.84536 2085 20.7097 2090 20.6386 2095 20.62427 2100 20.619