Year Percent 1950 40.9153 1955 40.91489 1960 41.04244 1965 31.61769 1970 21.23685 1975 21.36865 1980 21.04288 1985 22.51771 1990 24.27366 1995 25.43296 2000 28.5132 2005 28.45724 2010 29.45599 2015 29.40226 2020 28.46966 2025 29.65594 2030 30.19283 2035 31.10889 2040 31.43718 2045 31.11463 2050 30.74768 2055 30.49552 2060 30.39284 2065 30.25236 2070 29.96751 2075 29.58405 2080 29.16983 2085 28.77146 2090 28.421 2095 28.09912 2100 27.77259