Year Percent 1950 21.81739 1955 21.3886 1960 21.81981 1965 22.77976 1970 23.04452 1975 23.37662 1980 24.12323 1985 24.79024 1990 26.23797 1995 27.62596 2000 28.74339 2005 30.94202 2010 31.19054 2015 29.74389 2020 29.34355 2025 29.68112 2030 30.9014 2035 31.80124 2040 31.47067 2045 30.60237 2050 29.38033 2055 28.75235 2060 28.42321 2065 28.03292 2070 27.39033 2075 26.52959 2080 25.60347 2085 24.72114 2090 23.94554 2095 23.23762 2100 22.56219