Year Percent 1950 20.4297 1955 17.01693 1960 12.75432 1965 11.29846 1970 12.48567 1975 13.22016 1980 14.38549 1985 13.66019 1990 11.81909 1995 12.4925 2000 14.12932 2005 16.8391 2010 18.76097 2015 19.68032 2020 20.43607 2025 21.88551 2030 24.63294 2035 27.10548 2040 27.82482 2045 27.02946 2050 26.37162 2055 26.28244 2060 27.16213 2065 28.14124 2070 27.85664 2075 26.92491 2080 26.21141 2085 26.06068 2090 26.16682 2095 26.07564 2100 25.64564