Year Percent 1950 29.55176 1955 29.59639 1960 28.68203 1965 26.00025 1970 24.78456 1975 25.79265 1980 27.02528 1985 26.7988 1990 26.82504 1995 27.59318 2000 30.7261 2005 36.49335 2010 39.52622 2015 39.1182 2020 35.78191 2025 30.93005 2030 27.43533 2035 26.71218 2040 26.97035 2045 26.3578 2050 24.23179 2055 21.63864 2060 20.13534 2065 20.07933 2070 20.78962 2075 21.28178 2080 21.04343 2085 20.29894 2090 19.71305 2095 19.70664 2100 20.14836