Year Percent 1950 3.94752 1955 3.95007 1960 4.29958 1965 2.53765 1970 3.9 1975 3.47644 1980 3.37897 1985 3.4124 1990 3.4546 1995 3.47772 2000 3.39905 2005 2.90353 2010 3.14694 2015 3.75361 2020 4.79728 2025 6.27986 2030 8.28361 2035 10.93454 2040 13.75527 2045 15.21405 2050 16.41938 2055 17.91101 2060 21.28746 2065 25.15628 2070 29.00174 2075 33.15895 2080 36.3861 2085 37.90525 2090 38.31664 2095 38.42897 2100 38.15589