Year Percent 1950 28.29932 1955 25.9409 1960 25.29269 1965 21.99833 1970 23.47693 1975 21.31783 1980 27.62183 1985 30.39742 1990 32.89738 1995 31.48475 2000 30.19154 2005 24.42494 2010 21.68062 2015 19.06222 2020 20.27103 2025 22.10171 2030 24.11476 2035 25.11234 2040 24.56269 2045 23.51049 2050 22.3677 2055 22.91359 2060 23.16096 2065 23.26334 2070 22.83873 2075 22.02589 2080 21.21235 2085 20.81485 2090 20.84243 2095 20.96087 2100 20.9389