Year Percent 1950 13.69427 1955 14.78621 1960 14.96787 1965 15.55829 1970 15.93799 1975 16.32057 1980 16.82932 1985 16.87941 1990 16.86457 1995 17.07886 2000 15.61646 2005 14.39177 2010 13.2537 2015 13.02755 2020 12.70231 2025 12.2533 2030 11.43509 2035 10.62103 2040 9.98373 2045 9.49673 2050 9.02079 2055 8.51028 2060 8.00572 2065 7.56469 2070 7.21517 2075 6.93856 2080 6.69381 2085 6.46801 2090 6.24938 2095 6.06891 2100 5.92282