Year Percent 1950 15.77808 1955 18.43452 1960 18.48475 1965 18.699 1970 18.2263 1975 18.21894 1980 17.99575 1985 17.06264 1990 15.27058 1995 12.81335 2000 9.82153 2005 8.81983 2010 10.56881 2015 11.56386 2020 10.01289 2025 8.57258 2030 7.45558 2035 6.89573 2040 6.80546 2045 6.8602 2050 6.73818 2055 6.31083 2060 5.80059 2065 5.47461 2070 5.37401 2075 5.39699 2080 5.39628 2085 5.28831 2090 5.09758 2095 4.92048 2100 4.82787