Year Percent 1950 30.19273 1955 28.81348 1960 27.24392 1965 26.01104 1970 28.02416 1975 31.16842 1980 34.13874 1985 36.09354 1990 34.94502 1995 32.66021 2000 30.26576 2005 28.25155 2010 27.94419 2015 27.77471 2020 27.19917 2025 25.81323 2030 25.02617 2035 24.07127 2040 23.89253 2045 24.14078 2050 23.98266 2055 23.66461 2060 23.30226 2065 23.0337 2070 22.88837 2075 22.85076 2080 22.78686 2085 22.62139 2090 22.38143 2095 22.13469 2100 21.92696