Year Percent 1950 13.06434 1955 13.3392 1960 13.40715 1965 13.3397 1970 13.15893 1975 12.9768 1980 12.87489 1985 12.88186 1990 13.09871 1995 13.04826 2000 13.32343 2005 13.70018 2010 14.35343 2015 15.42015 2020 16.54295 2025 17.75424 2030 18.56781 2035 19.15207 2040 19.59814 2045 19.89862 2050 20.58021 2055 21.58976 2060 22.41268 2065 23.07964 2070 23.44717 2075 23.57972 2080 23.81636 2085 24.17289 2090 24.5378 2095 24.78637 2100 24.90653