Year Percent 1950 27.10773 1955 26.18664 1960 24.14188 1965 23.53347 1970 21.85005 1975 22.36057 1980 26.52902 1985 30.9732 1990 33.45349 1995 34.24293 2000 33.51837 2005 31.67612 2010 31.0761 2015 30.66553 2020 31.10147 2025 31.09994 2030 30.78471 2035 30.34536 2040 29.78544 2045 29.28439 2050 28.69621 2055 27.90378 2060 27.09607 2065 26.36442 2070 25.74736 2075 25.24078 2080 24.80731 2085 24.40794 2090 24.02033 2095 23.64062 2100 23.30359