Year Percent 1950 33.6415 1955 31.47464 1960 32.90356 1965 29.30795 1970 26.67174 1975 27.67431 1980 27.4607 1985 30.05032 1990 28.93452 1995 28.06482 2000 27.29507 2005 27.95577 2010 29.58606 2015 28.47957 2020 25.54431 2025 22.4995 2030 19.85624 2035 20.54406 2040 22.60388 2045 23.73875 2050 23.59625 2055 22.27149 2060 21.51655 2065 21.69795 2070 22.62125 2075 23.50543 2080 23.6584 2085 23.0846 2090 22.36189 2095 22.03188 2100 22.17562