Year Percent 1950 12.87417 1955 13.89396 1960 15.09958 1965 16.27389 1970 17.30326 1975 18.10921 1980 18.85338 1985 19.37065 1990 23.63677 1995 22.67989 2000 21.80813 2005 21.91535 2010 22.81946 2015 23.39712 2020 24.53381 2025 25.77587 2030 27.38004 2035 28.6024 2040 29.02926 2045 29.52849 2050 30.26685 2055 30.95272 2060 31.5339 2065 31.99496 2070 32.58521 2075 33.05861 2080 33.64755 2085 34.26362 2090 34.85958 2095 35.43705 2100 35.99595