Year Percent 1950 7.77326 1955 7.90939 1960 8.54042 1965 9.50929 1970 10.82384 1975 11.63685 1980 11.71268 1985 12.20576 1990 14.66574 1995 15.46297 2000 16.69568 2005 18.50606 2010 22.09202 2015 24.55264 2020 26.40631 2025 27.98366 2030 28.84565 2035 28.82057 2040 29.09167 2045 29.52766 2050 29.86645 2055 30.57962 2060 30.8687 2065 31.13722 2070 31.71275 2075 32.21253 2080 32.77109 2085 33.33192 2090 33.84357 2095 34.32433 2100 34.83089