Year Percent 1950 5.70792 1955 5.67302 1960 5.68943 1965 5.60301 1970 5.56669 1975 5.56902 1980 5.51803 1985 5.60955 1990 6.4825 1995 7.01919 2000 7.65568 2005 8.70373 2010 9.58285 2015 10.74433 2020 12.1806 2025 13.93728 2030 15.90874 2035 17.87724 2040 20.03792 2045 22.14545 2050 24.41754 2055 26.49118 2060 28.15223 2065 29.70998 2070 31.25064 2075 32.86998 2080 34.29968 2085 35.52179 2090 36.54556 2095 37.43185 2100 38.21334