Year Percent 1950 29.36283 1955 29.11317 1960 28.39941 1965 27.60421 1970 26.93137 1975 26.30963 1980 26.46414 1985 26.84809 1990 27.14231 1995 27.72029 2000 28.53459 2005 29.09647 2010 29.44268 2015 29.67866 2020 29.73873 2025 29.78629 2030 29.95651 2035 30.35254 2040 30.66101 2045 30.82895 2050 30.79916 2055 30.57597 2060 30.36524 2065 30.18153 2070 29.9969 2075 29.77201 2080 29.48913 2085 29.16978 2090 28.8489 2095 28.53578 2100 28.23072