Year Percent 1950 6.3269 1955 5.55591 1960 6.09123 1965 6.84401 1970 7.53265 1975 8.28327 1980 8.19296 1985 9.13401 1990 12.99768 1995 16.4968 2000 18.95074 2005 19.63054 2010 21.75782 2015 25.0569 2020 27.43954 2025 30.14234 2030 31.79916 2035 33.58547 2040 35.16111 2045 36.68274 2050 38.22079 2055 39.57206 2060 40.9683 2065 40.7549 2070 40.58553 2075 40.1954 2080 39.92149 2085 39.89854 2090 39.9191 2095 39.81098 2100 39.65014