Year Percent 1950 13.48472 1955 12.00925 1960 10.53434 1965 10.0291 1970 10.12275 1975 11.03363 1980 11.04213 1985 11.26723 1990 15.03231 1995 16.16205 2000 18.25892 2005 18.1752 2010 18.75949 2015 20.27858 2020 21.72286 2025 23.57873 2030 24.69204 2035 25.9104 2040 27.08507 2045 28.09207 2050 29.41233 2055 30.48157 2060 30.40331 2065 29.78086 2070 30.33557 2075 31.82674 2080 32.84681 2085 33.39703 2090 33.70531 2095 34.08495 2100 34.67156