Year	Percent
1967	33.76289
1968	70.13977
1969	74.6
1970	73.68914
1971	65.78737
1972	59.375
1973	67.82763
1974	73.72035
1975	67.5504
1976	62.33179
1977	58.30164
1978	58.32012
1979	61.06242
1980	62.65911
1981	64.68711
1982	58.54602
1983	53.6516
1984	50.28061
1985	49.82783
1986	39.24652
1987	48.87794
1988	40.0062
1990	47.23007
1991	43.06549
1992	44.71689
1993	43.05105
1994	43.00123
1995	44.03535
1996	49.81019
1997	50.03695
1998	41.96959
1999	48.6876
2000	53.68904
2001	51.7027
2002	49.10328
2003	49.75836
2004	51.37792
2005	58.27964
2006	56.17247
2007	56.48321
2008	58.48041
2009	50.63611
2010	65.65194
2011	72.74615
2012	67.98657
2013	71.48458
2014	66.0682
2015	51.79059
2016	41.22091