Year Percent 1950 29.6047 1955 28.0181 1960 26.92372 1965 25.55632 1970 25.23089 1975 27.42103 1980 29.31724 1985 32.55642 1990 35.19303 1995 35.77614 2000 35.42429 2005 34.05279 2010 33.08571 2015 30.57327 2020 28.54029 2025 26.24738 2030 22.59293 2035 21.47715 2040 21.65047 2045 21.66211 2050 21.24373 2055 20.48647 2060 20.05988 2065 20.16571 2070 20.53601 2075 20.86418 2080 20.96955 2085 20.84466 2090 20.65824 2095 20.56511 2100 20.59199