Year Percent 1950 9.25727 1955 8.024 1960 7.15448 1965 6.95913 1970 7.64263 1975 7.56102 1980 8.19648 1985 8.70559 1990 11.59679 1995 13.27533 2000 15.6328 2005 18.59052 2010 20.00651 2015 23.20193 2020 26.46546 2025 29.89583 2030 31.96461 2035 33.28872 2040 33.4325 2045 33.46179 2050 33.29386 2055 33.47083 2060 33.68023 2065 33.98736 2070 34.18375 2075 34.72535 2080 35.4621 2085 36.1394 2090 36.71221 2095 37.19257 2100 37.63612