Year Percent 1950 30.33601 1955 29.26924 1960 28.65537 1965 27.47069 1970 26.55548 1975 28.24275 1980 29.68556 1985 32.63829 1990 35.07995 1995 35.61968 2000 35.24189 2005 33.79543 2010 33.02869 2015 30.86491 2020 29.21658 2025 27.41797 2030 24.26217 2035 23.37657 2040 23.65818 2045 23.59226 2050 22.92436 2055 21.85469 2060 21.12813 2065 20.95589 2070 21.06019 2075 21.13469 2080 21.01212 2085 20.73159 2090 20.46956 2095 20.39105 2100 20.50569