Year Percent 1950 30.00449 1955 28.78738 1960 26.61159 1965 25.59101 1970 26.41769 1975 28.41338 1980 31.20638 1985 33.14429 1990 32.86974 1995 31.40873 2000 29.96102 2005 28.89132 2010 29.24242 2015 28.81854 2020 28.07568 2025 26.70957 2030 26.26665 2035 24.9943 2040 24.71274 2045 24.61814 2050 23.8702 2055 23.3038 2060 22.78901 2065 22.37102 2070 22.08875 2075 21.87226 2080 21.64431 2085 21.37307 2090 21.10048 2095 20.8823 2100 20.71707