Year Percent 1950 28.14054 1955 30.80597 1960 34.55529 1965 32.43875 1970 28.57044 1975 28.22758 1980 27.75586 1985 30.76814 1990 31.32048 1995 30.8141 2000 29.57086 2005 28.99977 2010 29.83745 2015 29.28356 2020 28.20455 2025 26.68358 2030 25.79025 2035 26.02154 2040 26.71416 2045 27.33299 2050 26.43103 2055 24.76985 2060 23.97533 2065 24.03234 2070 24.37069 2075 24.37448 2080 23.84898 2085 23.06948 2090 22.51315 2095 22.39113 2100 22.52941