Year Percent 1950 4.74608 1955 4.73926 1960 4.88455 1965 5.01577 1970 5.00033 1975 4.68117 1980 4.01315 1985 3.4383 1990 3.53247 1995 3.32126 2000 3.97969 2005 4.10936 2010 3.89856 2015 3.84296 2020 4.22625 2025 5.50321 2030 7.1482 2035 9.63783 2040 12.60138 2045 16.09356 2050 20.31932 2055 24.30311 2060 27.35238 2065 29.64331 2070 32.08435 2075 34.68251 2080 36.74808 2085 37.75233 2090 37.94142 2095 37.87444 2100 37.86858