Year Percent 1950 4.46002 1955 4.19668 1960 3.94733 1965 3.81724 1970 3.50836 1975 3.44352 1980 3.57544 1985 3.44515 1990 3.76192 1995 4.33261 2000 4.11493 2005 4.04868 2010 3.97651 2015 3.69093 2020 3.44309 2025 3.37335 2030 3.57314 2035 4.08984 2040 4.89068 2045 5.84493 2050 7.05204 2055 8.28564 2060 9.5385 2065 10.81931 2070 12.27614 2075 13.56511 2080 14.91919 2085 16.31442 2090 17.72176 2095 19.09943 2100 20.45254