Year Percent 1950 3.3193 1955 3.58534 1960 3.75795 1965 3.80122 1970 3.82064 1975 3.83883 1980 3.66475 1985 3.84904 1990 4.19107 1995 4.48073 2000 4.77003 2005 5.21185 2010 5.77398 2015 6.16769 2020 6.9299 2025 8.00003 2030 9.06914 2035 10.22598 2040 11.80661 2045 13.30457 2050 15.55626 2055 17.49387 2060 19.2236 2065 20.67634 2070 21.70279 2075 22.6689 2080 23.59712 2085 24.53845 2090 25.45845 2095 26.25729 2100 26.902