Year Percent 1950 4.87611 1955 4.95945 1960 5.11101 1965 5.31233 1970 5.333 1975 5.33012 1980 5.28738 1985 5.61056 1990 7.00022 1995 7.45596 2000 7.79069 2005 8.35968 2010 8.98033 2015 10.20191 2020 11.65761 2025 13.39786 2030 15.58924 2035 18.5427 2040 21.20735 2045 23.5829 2050 25.94499 2055 28.3114 2060 30.64387 2065 32.57262 2070 34.18245 2075 35.74297 2080 37.10193 2085 38.19761 2090 39.00606 2095 39.59615 2100 40.03216