Year Percent 1950 28.59852 1955 28.97761 1960 30.2435 1965 29.84197 1970 30.36425 1975 31.67491 1980 32.4553 1985 33.13464 1990 33.11021 1995 31.05337 2000 30.83901 2005 31.19929 2010 31.46739 2015 31.462 2020 29.93988 2025 27.6422 2030 25.19766 2035 23.55621 2040 23.13369 2045 23.05322 2050 23.12422 2055 22.65016 2060 21.97533 2065 21.46843 2070 21.36186 2075 21.58445 2080 21.82744 2085 21.83882 2090 21.58391 2095 21.25367 2100 21.06343