Year Percent 1950 27.24237 1955 28.11646 1960 31.82933 1965 29.31157 1970 26.8597 1975 27.89879 1980 29.8105 1985 33.52751 1990 34.0553 1995 31.0617 2000 28.70652 2005 28.57576 2010 31.029 2015 32.32076 2020 30.46361 2025 26.96224 2030 23.69404 2035 22.09123 2040 22.49274 2045 22.66421 2050 21.50755 2055 19.90697 2060 19.04824 2065 19.04939 2070 19.52705 2075 19.92286 2080 19.86931 2085 19.48221 2090 19.17195 2095 19.21665 2100 19.52194