Year Percent 1950 28.21197 1955 29.48183 1960 30.08233 1965 30.14093 1970 30.25231 1975 29.52741 1980 28.91441 1985 27.48205 1990 26.74312 1995 27.05004 2000 28.5706 2005 34.56977 2010 37.40191 2015 38.9329 2020 37.41141 2025 33.9641 2030 31.25775 2035 29.18209 2040 27.96484 2045 27.0709 2050 25.92484 2055 24.82572 2060 23.64664 2065 22.74033 2070 22.22531 2075 22.00356 2080 21.88229 2085 21.71193 2090 21.47313 2095 21.25466 2100 21.13408