Year Percent 1950 5.15184 1955 5.27159 1960 5.25934 1965 5.05228 1970 4.76645 1975 4.39236 1980 3.95325 1985 3.32635 1990 3.84922 1995 3.95657 2000 4.16593 2005 4.12946 2010 4.25149 2015 5.23715 2020 6.62194 2025 9.17272 2030 12.16105 2035 15.63309 2040 18.94044 2045 21.11162 2050 23.15009 2055 25.12346 2060 26.31364 2065 27.33458 2070 28.62246 2075 30.02963 2080 31.60678 2085 32.8131 2090 33.58471 2095 34.04963 2100 34.40496