Year Percent 1950 12.32881 1955 12.16222 1960 11.70994 1965 11.47055 1970 11.90885 1975 12.26504 1980 12.96339 1985 13.62361 1990 16.7157 1995 16.71536 2000 17.02974 2005 17.45161 2010 19.25624 2015 20.8875 2020 23.09157 2025 25.5454 2030 27.51371 2035 29.11433 2040 29.6635 2045 30.2516 2050 31.03193 2055 31.96468 2060 32.61102 2065 33.07431 2070 33.93602 2075 34.7932 2080 35.63086 2085 36.38249 2090 37.04262 2095 37.63686 2100 38.21962