Year Percent 1950 14.6775 1955 14.45334 1960 14.71422 1965 15.3545 1970 15.76575 1975 15.8539 1980 14.11762 1985 15.00337 1990 19.11657 1995 20.15915 2000 20.60516 2005 20.8688 2010 23.08865 2015 25.03625 2020 26.72848 2025 28.45908 2030 29.97445 2035 31.21056 2040 31.61681 2045 31.99757 2050 32.15672 2055 32.13724 2060 32.307 2065 32.69325 2070 33.22309 2075 33.70555 2080 34.15163 2085 34.58705 2090 35.06143 2095 35.59063 2100 36.1037