Year Percent 1950 15.18633 1955 15.08016 1960 14.98267 1965 14.82391 1970 14.6231 1975 14.29518 1980 14.03931 1985 13.73891 1990 13.15429 1995 13.4689 2000 14.06535 2005 15.145 2010 16.23916 2015 16.99351 2020 17.50433 2025 18.01848 2030 19.08352 2035 21.12142 2040 24.84568 2045 28.56012 2050 30.91845 2055 31.26815 2060 30.08839 2065 28.59696 2070 27.55108 2075 27.03974 2080 26.19226 2085 25.24301 2090 24.45987 2095 24.01277 2100 23.7833