Year Percent 1950 5.29926 1955 4.84196 1960 4.19049 1965 3.89508 1970 3.42746 1975 3.05165 1980 2.9607 1985 3.07077 1990 3.28015 1995 3.48181 2000 3.78416 2005 4.1096 2010 4.45086 2015 5.11725 2020 5.74125 2025 6.36311 2030 7.23363 2035 8.63466 2040 10.78145 2045 13.39549 2050 15.57818 2055 17.31989 2060 18.62365 2065 19.62047 2070 20.74442 2075 22.29147 2080 23.76061 2085 25.04947 2090 26.12096 2095 27.03303 2100 27.86158