Year Percent 1950 28.34125 1955 30.97686 1960 33.36183 1965 34.50257 1970 32.35497 1975 25.93212 1980 32.62383 1985 32.42171 1990 33.86816 1995 33.46612 2000 34.54791 2005 37.50459 2010 37.43101 2015 36.89892 2020 35.64949 2025 34.14892 2030 32.45679 2035 31.51142 2040 30.92979 2045 30.37294 2050 29.74294 2055 28.62527 2060 27.62291 2065 26.77314 2070 26.11304 2075 25.59081 2080 25.10627 2085 24.60505 2090 24.10649 2095 23.65543 2100 23.30163