Year Percent 1950 20.06016 1955 21.97023 1960 21.17768 1965 20.89823 1970 19.61344 1975 17.96087 1980 17.29425 1985 16.45107 1990 17.56099 1995 19.68745 2000 20.96808 2005 21.59187 2010 21.18188 2015 20.78464 2020 21.29465 2025 21.72101 2030 21.8634 2035 21.40411 2040 21.1022 2045 21.11692 2050 21.63939 2055 22.69416 2060 23.22638 2065 23.43362 2070 23.29514 2075 22.87241 2080 22.81419 2085 22.98747 2090 23.16315 2095 23.15244 2100 22.92152