Year Percent 1950 4.17375 1955 3.93507 1960 3.93058 1965 3.97204 1970 4.03785 1975 4.06407 1980 4.03757 1985 4.0004 1990 4.24549 1995 4.17774 2000 4.0539 2005 3.94089 2010 3.82681 2015 3.71439 2020 3.68416 2025 3.80173 2030 4.09744 2035 4.63848 2040 5.31912 2045 6.01349 2050 6.71384 2055 7.45348 2060 8.31699 2065 9.27345 2070 10.20315 2075 11.13366 2080 12.1194 2085 13.15459 2090 14.21569 2095 15.28015 2100 16.3433