Year Percent 1950 22.50449 1955 24.17927 1960 23.27324 1965 23.86873 1970 23.77061 1975 23.54362 1980 25.32465 1985 24.8982 1990 25.43246 1995 25.83657 2000 26.35777 2005 28.13127 2010 29.35589 2015 30.72045 2020 30.53347 2025 28.5589 2030 25.99978 2035 23.64797 2040 22.40911 2045 22.28356 2050 22.68849 2055 22.86083 2060 22.91652 2065 22.68424 2070 22.26946 2075 22.22074 2080 22.3306 2085 22.45251 2090 22.42849 2095 22.22873 2100 21.94612