Year Percent 1950 15.97963 1955 16.35107 1960 16.62062 1965 16.76173 1970 16.63172 1975 16.18692 1980 15.70174 1985 15.06686 1990 14.30533 1995 14.52848 2000 14.26509 2005 14.71661 2010 15.72251 2015 17.04229 2020 19.05312 2025 21.20729 2030 23.55949 2035 25.96998 2040 28.26685 2045 29.88011 2050 30.32538 2055 29.32852 2060 27.94052 2065 26.663 2070 25.72623 2075 25.36562 2080 24.67524 2085 23.8764 2090 23.23503 2095 22.90676 2100 22.77153