Year Percent 1950 28.28354 1955 28.64997 1960 28.958 1965 28.12849 1970 27.21686 1975 27.55117 1980 29.03442 1985 31.56915 1990 34.1581 1995 35.21495 2000 34.43413 2005 33.71239 2010 31.51717 2015 28.95634 2020 27.91627 2025 27.31522 2030 26.9528 2035 25.8083 2040 24.122 2045 22.83913 2050 21.93695 2055 21.3905 2060 21.31738 2065 21.34733 2070 21.19981 2075 20.93261 2080 20.73366 2085 20.69183 2090 20.79586 2095 20.96027 2100 21.05801