Year Percent 1950 14.83535 1955 15.64335 1960 16.27152 1965 15.08158 1970 15.19561 1975 15.42064 1980 15.89756 1985 16.84488 1990 17.80786 1995 20.15147 2000 22.73501 2005 25.56514 2010 28.62606 2015 29.04538 2020 26.06034 2025 21.35928 2030 18.1097 2035 17.91045 2040 20.84069 2045 24.37467 2050 26.95894 2055 26.77443 2060 24.82238 2065 23.25025 2070 22.78737 2075 22.84569 2080 23.30619 2085 23.27612 2090 22.58812 2095 21.78205 2100 21.42474