Year Percent 1950 25.94397 1955 25.26931 1960 27.24583 1965 28.22535 1970 28.43533 1975 29.10974 1980 30.21448 1985 31.21869 1990 32.81017 1995 34.02119 2000 31.73756 2005 29.11714 2010 26.89552 2015 26.99106 2020 26.27332 2025 24.55067 2030 22.84119 2035 21.42544 2040 21.23514 2045 21.55639 2050 21.90127 2055 21.92629 2060 21.59385 2065 21.20859 2070 21.06052 2075 21.22853 2080 21.51387 2085 21.65858 2090 21.53767 2095 21.23419 2100 20.94116