Year Percent 1950 4.38341 1955 3.99019 1960 3.73262 1965 3.58036 1970 3.55579 1975 3.61702 1980 3.72719 1985 3.86193 1990 4.24941 1995 4.79576 2000 5.10757 2005 5.122 2010 5.18061 2015 4.9238 2020 4.76357 2025 4.65893 2030 4.64525 2035 4.87319 2040 5.69589 2045 7.10545 2050 8.54682 2055 9.54039 2060 10.50028 2065 11.95865 2070 13.74466 2075 15.40192 2080 16.93648 2085 18.40906 2090 19.9171 2095 21.51731 2100 23.16428