Year Percent 1950 13.27894 1955 13.25872 1960 13.33873 1965 13.36693 1970 13.19043 1975 13.40168 1980 13.91891 1985 13.94491 1990 14.84974 1995 16.49279 2000 18.13302 2005 19.24488 2010 20.24857 2015 20.84602 2020 21.58712 2025 23.32843 2030 25.5805 2035 27.71725 2040 29.06795 2045 28.62629 2050 27.07411 2055 25.54543 2060 24.84048 2065 24.93035 2070 25.23197 2075 25.15105 2080 24.55335 2085 23.77697 2090 23.24737 2095 23.11597 2100 23.20221