Year Percent 1950 20.93776 1955 19.30358 1960 19.95889 1965 18.02668 1970 18.73554 1975 20.86211 1980 23.44675 1985 26.99086 1990 30.64963 1995 32.7804 2000 33.17934 2005 32.65169 2010 32.14247 2015 31.73324 2020 31.30108 2025 30.28553 2030 29.5633 2035 28.48752 2040 27.46055 2045 26.64789 2050 25.46918 2055 24.42534 2060 23.49006 2065 22.76296 2070 22.23257 2075 21.77055 2080 21.29966 2085 20.83391 2090 20.42435 2095 20.10155 2100 19.8726