Year Percent 1950 5.48693 1955 5.22368 1960 5.22702 1965 5.21646 1970 5.29191 1975 5.4566 1980 5.51997 1985 5.74307 1990 6.72159 1995 7.06775 2000 7.57798 2005 8.36105 2010 9.77967 2015 11.75835 2020 14.06176 2025 16.78694 2030 19.66001 2035 21.93818 2040 24.42195 2045 27.06651 2050 29.5396 2055 31.82361 2060 33.64985 2065 35.33333 2070 36.66989 2075 37.66645 2080 38.39282 2085 38.86998 2090 39.18229 2095 39.38986 2100 39.54326