Year Percent 1950 19.13682 1955 18.25609 1960 18.1649 1965 17.16874 1970 16.3605 1975 16.12822 1980 16.31972 1985 16.49408 1990 17.11582 1995 19.62299 2000 21.76235 2005 25.23247 2010 29.02023 2015 30.43826 2020 30.56482 2025 29.98034 2030 30.15607 2035 29.01857 2040 28.14591 2045 26.86087 2050 24.06389 2055 23.59066 2060 24.32732 2065 24.7023 2070 24.37837 2075 23.50507 2080 22.90571 2085 22.8445 2090 23.0321 2095 23.13264 2100 22.98873