Year Percent 1950 29.34311 1955 28.56196 1960 27.68067 1965 27.14348 1970 26.32428 1975 27.0679 1980 29.26903 1985 30.88191 1990 32.94855 1995 33.53672 2000 32.95169 2005 32.48355 2010 31.66951 2015 31.02247 2020 30.44619 2025 29.17005 2030 27.88665 2035 27.00047 2040 26.00931 2045 25.05262 2050 24.47133 2055 23.59499 2060 22.86557 2065 22.33626 2070 21.88092 2075 21.47924 2080 21.11411 2085 20.7788 2090 20.48409 2095 20.24739 2100 20.06671