Year Percent 1950 4.23487 1955 4.46084 1960 4.60166 1965 4.75426 1970 4.73033 1975 4.45757 1980 4.4806 1985 4.93194 1990 6.07099 1995 6.62717 2000 6.98907 2005 7.58725 2010 8.12881 2015 9.5494 2020 11.49477 2025 13.51454 2030 15.0745 2035 16.45796 2040 18.01787 2045 20.12135 2050 22.34263 2055 24.67078 2060 26.41463 2065 28.01038 2070 29.5918 2075 31.55019 2080 33.15362 2085 34.4075 2090 35.38272 2095 36.19455 2100 36.96372