Year Percent 1950 16.5371 1955 15.97923 1960 16.34632 1965 16.2974 1970 15.80492 1975 15.63967 1980 17.32816 1985 19.07664 1990 21.28131 1995 24.38541 2000 28.69415 2005 30.8388 2010 32.0883 2015 30.95185 2020 28.47601 2025 25.74983 2030 24.16104 2035 23.55467 2040 23.89523 2045 24.12632 2050 24.11875 2055 23.98435 2060 24.03659 2065 24.05841 2070 24.23579 2075 24.04761 2080 23.63437 2085 23.27177 2090 23.04089 2095 22.8984 2100 22.7706