Year Percent 1950 27.0086 1955 27.40741 1960 27.21085 1965 27.2748 1970 28.31913 1975 29.66277 1980 31.22532 1985 32.04712 1990 32.93187 1995 33.03788 2000 32.46051 2005 32.10454 2010 30.70226 2015 29.49131 2020 27.39293 2025 26.28552 2030 26.13307 2035 25.73135 2040 25.16999 2045 23.89503 2050 22.39019 2055 21.5751 2060 21.23653 2065 21.09252 2070 20.81727 2075 20.26406 2080 19.59577 2085 19.11818 2090 18.96899 2095 19.01942 2100 19.05135