Year Percent 1950 29.7121 1955 28.31676 1960 28.69853 1965 26.82387 1970 26.70248 1975 28.3889 1980 29.80824 1985 30.24646 1990 29.48004 1995 28.75932 2000 29.37202 2005 30.25165 2010 30.54108 2015 29.29005 2020 26.27248 2025 23.27773 2030 21.21032 2035 20.15988 2040 20.42791 2045 20.9958 2050 20.82858 2055 20.26769 2060 19.73023 2065 19.5633 2070 19.88453 2075 20.482 2080 20.91131 2085 20.91685 2090 20.63237 2095 20.34892 2100 20.25698