Year Percent 1950 28.69191 1955 29.54949 1960 30.85212 1965 30.31381 1970 30.23148 1975 31.38266 1980 31.7122 1985 32.3355 1990 32.14834 1995 30.0402 2000 29.71705 2005 29.76077 2010 29.98679 2015 29.91887 2020 28.39115 2025 26.16972 2030 23.79637 2035 22.19638 2040 21.81269 2045 21.7667 2050 21.84203 2055 21.42625 2060 20.82703 2065 20.40282 2070 20.373 2075 20.66988 2080 20.99402 2085 21.08429 2090 20.90137 2095 20.6202 2100 20.4568