Year Percent 1950 18.26147 1955 20.52899 1960 19.95031 1965 20.63073 1970 19.6258 1975 17.51826 1980 16.19131 1985 14.99164 1990 14.4168 1995 14.79882 2000 14.73299 2005 14.03063 2010 13.98424 2015 12.57879 2020 11.37697 2025 10.93771 2030 10.84115 2035 10.82131 2040 10.50622 2045 9.8247 2050 9.01638 2055 8.38235 2060 8.06284 2065 7.8768 2070 7.61465 2075 7.17438 2080 6.66172 2085 6.21675 2090 5.93769 2095 5.7738 2100 5.63577