Year Percent 1950 14.78018 1955 14.23337 1960 13.67978 1965 11.10415 1970 11.44371 1975 11.86618 1980 8.69546 1985 8.70083 1990 10.83516 1995 11.2778 2000 11.58856 2005 13.87806 2010 15.83587 2015 21.03239 2020 25.55048 2025 29.72983 2030 31.46574 2035 30.53345 2040 28.96823 2045 27.18327 2050 26.92972 2055 27.7014 2060 27.6344 2065 27.10854 2070 26.10096 2075 25.24522 2080 25.00069 2085 24.8406 2090 24.5422 2095 24.13319 2100 23.73406