Year Percent 1950 53.11975 1955 47.056 1960 40.8652 1965 38.70372 1970 36.55327 1975 35.87982 1980 35.33962 1985 37.09111 1990 38.55934 1995 35.95723 2000 32.7672 2005 29.56853 2010 28.07598 2015 28.17157 2020 29.28918 2025 30.01942 2030 29.58201 2035 28.37917 2040 27.05903 2045 26.23043 2050 25.87215 2055 25.50337 2060 24.89674 2065 24.05283 2070 23.19832 2075 22.52761 2080 22.08211 2085 21.77879 2090 21.49075 2095 21.13946 2100 20.76997