Year Percent 1950 3.7445 1955 3.39394 1960 3.0437 1965 2.75189 1970 2.78081 1975 3.02881 1980 3.29857 1985 3.53977 1990 3.77643 1995 4.25749 2000 5.20685 2005 6.01987 2010 6.22964 2015 6.63197 2020 8.04386 2025 9.96693 2030 12.22382 2035 14.67342 2040 17.53356 2045 21.96695 2050 26.96881 2055 30.73294 2060 32.59317 2065 33.45678 2070 34.62535 2075 36.51668 2080 38.17349 2085 39.05388 2090 39.20057 2095 39.15992 2100 39.42186