Year Percent 1950 21.68923 1955 21.7647 1960 21.47694 1965 21.18099 1970 20.86572 1975 19.72682 1980 19.89508 1985 20.09887 1990 21.70645 1995 23.26067 2000 25.45091 2005 26.91608 2010 26.57889 2015 26.10067 2020 24.55927 2025 23.09638 2030 22.94422 2035 23.67452 2040 24.63143 2045 24.89459 2050 24.88659 2055 24.20184 2060 23.95444 2065 24.09691 2070 23.79413 2075 23.51791 2080 23.21723 2085 22.96752 2090 22.79254 2095 22.68409 2100 22.56668