Year Percent 1950 7.2392 1955 8.01381 1960 7.15251 1965 6.63561 1970 7.70006 1975 8.46997 1980 8.19439 1985 6.66302 1990 5.6012 1995 5.98084 2000 5.78256 2005 5.91882 2010 5.22865 2015 4.79775 2020 4.60364 2025 4.65773 2030 4.85138 2035 4.87032 2040 4.72231 2045 4.52226 2050 4.42958 2055 4.49368 2060 4.64736 2065 4.78101 2070 4.80702 2075 4.7514 2080 4.68723 2085 4.68225 2090 4.72462 2095 4.77438 2100 4.78359