Year Percent 1950 27.84566 1955 29.77841 1960 32.57769 1965 31.97823 1970 31.89304 1975 31.14845 1980 31.07355 1985 32.46484 1990 31.45185 1995 29.11289 2000 28.63779 2005 28.34888 2010 28.25672 2015 27.32618 2020 26.168 2025 24.41607 2030 23.58395 2035 23.4096 2040 22.7399 2045 22.57438 2050 21.70628 2055 21.00383 2060 20.7374 2065 20.81587 2070 20.98442 2075 21.07304 2080 20.99374 2085 20.79353 2090 20.64964 2095 20.6748 2100 20.80254