Year Percent 1950 4.04167 1955 3.85082 1960 3.74226 1965 3.73504 1970 3.83787 1975 4.04933 1980 4.35847 1985 4.79309 1990 5.9492 1995 6.77149 2000 7.55804 2005 8.13844 2010 8.93492 2015 10.09966 2020 11.62765 2025 13.36466 2030 15.15259 2035 16.96517 2040 18.79501 2045 20.796 2050 22.80471 2055 24.83083 2060 26.64904 2065 28.56179 2070 30.45085 2075 32.25486 2080 33.86539 2085 35.27457 2090 36.49865 2095 37.53978 2100 38.40549