Year Percent 1950 10.24432 1955 10.63284 1960 11.14864 1965 11.92762 1970 13.14643 1975 14.06394 1980 13.41469 1985 14.44051 1990 17.82285 1995 19.49823 2000 21.42675 2005 22.39932 2010 24.25755 2015 26.00712 2020 28.24911 2025 31.24938 2030 34.2631 2035 36.86048 2040 38.149 2045 38.37318 2050 38.1101 2055 37.67792 2060 37.13972 2065 36.83919 2070 36.8861 2075 36.8242 2080 36.82247 2085 36.88892 2090 37.05611 2095 37.33944 2100 37.68793