Year Percent 1950 9.78254 1955 9.45136 1960 10.23748 1965 10.74565 1970 11.05661 1975 11.25283 1980 10.20504 1985 9.96013 1990 12.41721 1995 14.36838 2000 15.984 2005 16.66656 2010 17.695 2015 19.38803 2020 21.23354 2025 23.06595 2030 24.46829 2035 26.60414 2040 28.48045 2045 30.49026 2050 32.92916 2055 33.45192 2060 32.40191 2065 31.88546 2070 32.65579 2075 32.95851 2080 33.38601 2085 33.72652 2090 33.81908 2095 33.88483 2100 34.18373