Year Percent 1950 28.86925 1955 27.90064 1960 26.97888 1965 27.13277 1970 27.52523 1975 29.41699 1980 31.69334 1985 33.31821 1990 34.35598 1995 33.80512 2000 32.65773 2005 31.75576 2010 31.37904 2015 31.27537 2020 30.90617 2025 29.82297 2030 28.21431 2035 26.61165 2040 25.4444 2045 24.62423 2050 23.86232 2055 23.26433 2060 22.69909 2065 22.20017 2070 21.80109 2075 21.53156 2080 21.35829 2085 21.2246 2090 21.08933 2095 20.94768 2100 20.81191