Year Percent 1950 3.99978 1955 3.72438 1960 3.82615 1965 4.00188 1970 4.27382 1975 4.32689 1980 4.13859 1985 3.96354 1990 4.09405 1995 4.25856 2000 4.47015 2005 4.77191 2010 5.73354 2015 6.45064 2020 7.30449 2025 8.16587 2030 9.03017 2035 9.76241 2040 10.51118 2045 11.21772 2050 12.10961 2055 13.3769 2060 14.70335 2065 15.93348 2070 17.11373 2075 18.37253 2080 19.66816 2085 20.96714 2090 22.26741 2095 23.5628 2100 24.83368