Year Percent 1950 4.6946 1955 3.7935 1960 3.48164 1965 3.58005 1970 3.74634 1975 4.00725 1980 2.85481 1985 2.76174 1990 2.91601 1995 3.22633 2000 3.59876 2005 3.96073 2010 4.77308 2015 5.04264 2020 5.26422 2025 5.51585 2030 5.93409 2035 6.41174 2040 5.7846 2045 5.97857 2050 6.15683 2055 6.81175 2060 8.50589 2065 9.84263 2070 11.47888 2075 13.21159 2080 14.86294 2085 16.60477 2090 18.43182 2095 20.26908 2100 22.05565