Year Percent 1950 13.16954 1955 16.29181 1960 17.33083 1965 18.49898 1970 19.80849 1975 20.59451 1980 20.36563 1985 20.08904 1990 19.15302 1995 16.30122 2000 16.64527 2005 16.68127 2010 16.75562 2015 14.75627 2020 13.21995 2025 12.31147 2030 11.71115 2035 11.14924 2040 10.47915 2045 9.73475 2050 8.98692 2055 8.33939 2060 7.81294 2065 7.35841 2070 6.94862 2075 6.5496 2080 6.17892 2085 5.85479 2090 5.58617 2095 5.3784 2100 5.20524