Year Percent 1950 21.40704 1955 22.55344 1960 22.62424 1965 22.13304 1970 20.59195 1975 18.2251 1980 17.27564 1985 17.33613 1990 19.77199 1995 22.2347 2000 23.87029 2005 25.01326 2010 24.9702 2015 26.46976 2020 27.82034 2025 28.14155 2030 27.25372 2035 24.75592 2040 22.55285 2045 21.61436 2050 22.63071 2055 24.2412 2060 25.02608 2065 24.6273 2070 23.41995 2075 22.4785 2080 22.31734 2085 22.69005 2090 23.04136 2095 22.96705 2100 22.49237