Year Percent 1950 12.89497 1955 12.84102 1960 14.31345 1965 15.81908 1970 13.48223 1975 10.38041 1980 9.25011 1985 7.58911 1990 7.02002 1995 7.09729 2000 7.71814 2005 6.59108 2010 5.71521 2015 5.08496 2020 4.74432 2025 4.43684 2030 4.2048 2035 4.08236 2040 3.91866 2045 3.75562 2050 3.64077 2055 3.58493 2060 3.56983 2065 3.57344 2070 3.56663 2075 3.54219 2080 3.50792 2085 3.48889 2090 3.47534 2095 3.47197 2100 3.4647