Year	Percent
1960	48.29395
1961	41.97456
1962	47.85754
1963	59.22838
1964	53.86225
1965	65.93625
1966	73.22404
1967	73.59551
1968	75.61404
1969	64.94024
1970	69.91261
1971	67.82787
1972	67.02128
1973	70.38961
1974	81.51448
1975	72.93621
1976	75.6962
1977	65.39334
1978	62.93045
1979	62.89997
1980	74.60141
1981	75.18467
1982	66.38684
1983	62.13027
1984	55.50377
1985	56.6729
1986	68.77131
1987	81.84646
1988	76.87028
1989	84.11205
1990	59.02125
1991	59.25919
1992	57.34916
1993	57.28558
1994	63.67868
1995	60.01572
1996	59.35483
1997	61.35077
1998	67.17377
1999	64.9999
2000	68.75679
2001	74.74217
2002	77.17426
2003	84.44439
2004	68.62698
2005	60.38438
2006	59.1296
2007	57.25964
2008	54.43781
2009	51.95156
2010	46.47111
2011	45.75039
2012	44.94757
2013	46.65123
2014	50.24535
2015	49.63082
2016	49.51635