Year Percent 1950 29.67466 1955 27.81967 1960 24.71945 1965 22.34681 1970 22.00109 1975 21.85705 1980 27.24035 1985 30.11263 1990 32.98825 1995 32.00408 2000 31.20435 2005 27.51845 2010 20.6776 2015 20.37027 2020 22.76209 2025 25.712 2030 27.64696 2035 26.88608 2040 24.71745 2045 23.20808 2050 22.91862 2055 23.15485 2060 23.67072 2065 23.50025 2070 22.5057 2075 21.35452 2080 20.69148 2085 20.62404 2090 20.86406 2095 21.00427 2100 20.81677