Year Percent 1950 3.42916 1955 3.36945 1960 3.47664 1965 3.61833 1970 3.82252 1975 4.12558 1980 4.42525 1985 4.67563 1990 5.26668 1995 5.5601 2000 6.07756 2005 6.76142 2010 7.5735 2015 8.58899 2020 9.98687 2025 11.84161 2030 13.52188 2035 14.86006 2040 16.34713 2045 17.95505 2050 19.79483 2055 21.48432 2060 23.05746 2065 24.64525 2070 26.25155 2075 27.80745 2080 29.22395 2085 30.47178 2090 31.57583 2095 32.52617 2100 33.34131