Year Percent 1950 3.38524 1955 3.24444 1960 3.08415 1965 3.15511 1970 3.22607 1975 3.91217 1980 4.60492 1985 5.46597 1990 7.04746 1995 7.63216 2000 8.8002 2005 9.87921 2010 11.97205 2015 14.16972 2020 16.33219 2025 18.89341 2030 21.00894 2035 22.80183 2040 23.83249 2045 24.78046 2050 26.22008 2055 28.01558 2060 29.77002 2065 31.56012 2070 32.98604 2075 34.32077 2080 35.64748 2085 36.96134 2090 38.13243 2095 39.09524 2100 39.86734