Year Percent 1950 7.40576 1955 7.25405 1960 5.5154 1965 5.52099 1970 5.47942 1975 5.51961 1980 5.58591 1985 6.25425 1990 7.88446 1995 8.61985 2000 8.74454 2005 9.41021 2010 10.19775 2015 11.21673 2020 12.55866 2025 15.00589 2030 16.82718 2035 18.90079 2040 20.11854 2045 21.59818 2050 22.9467 2055 24.57309 2060 26.05071 2065 27.34835 2070 28.59612 2075 29.89514 2080 31.07849 2085 32.13514 2090 33.0737 2095 33.8755 2100 34.5498