Year Percent 1950 13.91639 1955 14.26692 1960 12.88537 1965 13.49405 1970 13.84281 1975 14.43979 1980 14.71583 1985 14.85761 1990 14.53457 1995 15.74313 2000 14.12046 2005 12.117 2010 10.46806 2015 9.73481 2020 8.77509 2025 8.27524 2030 7.56298 2035 6.83556 2040 6.22437 2045 5.80151 2050 5.53702 2055 5.35174 2060 5.17141 2065 4.98161 2070 4.81648 2075 4.71361 2080 4.67983 2085 4.68372 2090 4.68841 2095 4.67291 2100 4.64786