Year Percent 1950 26.23296 1955 26.44377 1960 26.66971 1965 25.60546 1970 24.31991 1975 22.82087 1980 23.44866 1985 23.42087 1990 24.61275 1995 25.81328 2000 27.40158 2005 28.87021 2010 30.21788 2015 30.23791 2020 29.63754 2025 28.31249 2030 26.93301 2035 26.25337 2040 25.62607 2045 25.04252 2050 24.74119 2055 24.32666 2060 24.11055 2065 24.01724 2070 23.89669 2075 23.81213 2080 23.71623 2085 23.56472 2090 23.3654 2095 23.15065 2100 22.95906