Year Percent 1950 6.11143 1955 7.58639 1960 7.4035 1965 7.69295 1970 7.82495 1975 7.06791 1980 6.35911 1985 5.77266 1990 5.68516 1995 5.68932 2000 5.753 2005 5.40957 2010 5.28883 2015 5.56054 2020 5.52022 2025 5.51409 2030 5.37856 2035 5.21354 2040 5.11572 2045 5.14567 2050 5.21921 2055 5.25403 2060 5.23648 2065 5.17413 2070 5.11634 2075 5.09314 2080 5.10173 2085 5.10185 2090 5.077 2095 5.0179 2100 4.95116