Year Percent 1950 30.09418 1955 28.48137 1960 28.87157 1965 27.17656 1970 27.26264 1975 29.40194 1980 31.44243 1985 32.38511 1990 31.72314 1995 31.07875 2000 31.93561 2005 33.11192 2010 33.71506 2015 32.396 2020 28.92877 2025 25.59328 2030 23.4101 2035 22.27126 2040 22.53541 2045 23.09206 2050 22.82416 2055 22.13559 2060 21.46974 2065 21.208 2070 21.46154 2075 21.98727 2080 22.31977 2085 22.20574 2090 21.81504 2095 21.46487 2100 21.34881