Year Percent 1950 16.97054 1955 17.37832 1960 17.35322 1965 17.39432 1970 17.49501 1975 17.39106 1980 17.66849 1985 17.57906 1990 18.5367 1995 19.24327 2000 19.96043 2005 19.1619 2010 18.769 2015 18.14631 2020 17.89448 2025 17.31075 2030 16.60848 2035 15.84128 2040 15.07308 2045 14.36348 2050 13.69087 2055 12.99404 2060 12.30819 2065 11.64805 2070 11.05387 2075 10.49677 2080 9.97756 2085 9.4803 2090 9.00359 2095 8.54152 2100 8.12769