Year Percent 1950 24.35006 1955 24.40286 1960 21.53183 1965 21.22946 1970 21.97468 1975 22.96188 1980 24.45702 1985 24.32063 1990 24.5558 1995 26.27649 2000 27.72765 2005 29.26597 2010 30.16936 2015 29.14568 2020 29.09688 2025 28.89659 2030 28.19609 2035 26.70821 2040 24.15779 2045 21.87079 2050 21.04585 2055 21.68231 2060 22.71996 2065 23.51438 2070 23.15421 2075 22.33646 2080 21.84939 2085 21.93752 2090 22.37762 2095 22.6964 2100 22.56993