Year Percent 1950 14.13884 1955 14.09757 1960 13.862 1965 13.56435 1970 13.04685 1975 12.30992 1980 11.58515 1985 10.93046 1990 10.34873 1995 10.52157 2000 11.23698 2005 12.05629 2010 12.58325 2015 11.63016 2020 11.38297 2025 11.91649 2030 12.9808 2035 14.15497 2040 14.6257 2045 14.92108 2050 15.63085 2055 16.68773 2060 18.02889 2065 19.17813 2070 19.81142 2075 20.24544 2080 20.7476 2085 21.42876 2090 22.17176 2095 22.78204 2100 23.18146