Year Percent 1950 28.49383 1955 33.83779 1960 37.03556 1965 37.92093 1970 35.41588 1975 27.28651 1980 35.54154 1985 35.1077 1990 35.87037 1995 34.95605 2000 36.32217 2005 37.97036 2010 38.20483 2015 37.59456 2020 35.89124 2025 33.82917 2030 32.07261 2035 31.34716 2040 30.96847 2045 30.64671 2050 30.22263 2055 29.28804 2060 28.42725 2065 27.67348 2070 27.07098 2075 26.56775 2080 26.06818 2085 25.52482 2090 24.9684 2095 24.4537 2100 24.03102