Year Percent 1950 27.71532 1955 27.91755 1960 28.11617 1965 28.1158 1970 28.06327 1975 27.41636 1980 26.88068 1985 25.9783 1990 25.53914 1995 25.64038 2000 25.74194 2005 26.6415 2010 27.37759 2015 29.01961 2020 31.16831 2025 32.60934 2030 33.38146 2035 33.50536 2040 33.07488 2045 32.54477 2050 32.0854 2055 31.41095 2060 30.56127 2065 29.63973 2070 28.73611 2075 27.86211 2080 27.03439 2085 26.23197 2090 25.46605 2095 24.75879 2100 24.12041