Year Percent 1950 28.28792 1955 27.38249 1960 25.97931 1965 25.30904 1970 23.7365 1975 24.1993 1980 24.34765 1985 25.87198 1990 27.80772 1995 28.35338 2000 29.5198 2005 31.14469 2010 32.63489 2015 33.0975 2020 32.56816 2025 31.63105 2030 31.61031 2035 32.40123 2040 32.83941 2045 32.76888 2050 32.0402 2055 30.92699 2060 30.1892 2065 29.68151 2070 29.14602 2075 28.40127 2080 27.5208 2085 26.61901 2090 25.80829 2095 25.13189 2100 24.53957