Year Percent 1950 16.68137 1955 16.59317 1960 14.06495 1965 12.86049 1970 15.29141 1975 17.1373 1980 20.60082 1985 19.41564 1990 17.98486 1995 19.29702 2000 21.28742 2005 25.64256 2010 26.42801 2015 25.71858 2020 24.34468 2025 25.03849 2030 28.29364 2035 30.56759 2040 30.00097 2045 27.66209 2050 25.38205 2055 24.75424 2060 25.63089 2065 26.12106 2070 24.94716 2075 23.125 2080 22.13457 2085 22.15228 2090 22.67729 2095 23.01575 2100 22.75378