Year Percent 1950 11.98304 1955 12.33789 1960 12.29632 1965 12.07808 1970 11.75619 1975 12.42557 1980 13.02927 1985 13.87727 1990 16.95847 1995 17.28399 2000 17.80385 2005 18.63055 2010 19.98354 2015 21.32334 2020 22.86695 2025 24.48037 2030 25.72505 2035 26.9624 2040 27.62649 2045 28.63452 2050 29.58088 2055 30.23391 2060 30.58429 2065 30.92413 2070 31.63102 2075 32.4347 2080 33.32587 2085 34.09785 2090 34.78899 2095 35.46168 2100 36.18131