Year Percent 1950 3.99631 1955 4.00583 1960 4.12973 1965 4.32969 1970 4.42309 1975 4.49181 1980 4.81327 1985 4.81077 1990 4.9747 1995 4.88311 2000 4.91162 2005 4.95102 2010 5.01656 2015 5.52163 2020 6.10953 2025 6.91749 2030 7.86514 2035 9.01775 2040 10.41216 2045 12.27743 2050 14.622 2055 17.21318 2060 19.41143 2065 21.24279 2070 23.18267 2075 25.02106 2080 26.75062 2085 28.29201 2090 29.65977 2095 30.86762 2100 31.92176