Year	Percent
1975	70.81818
1976	56.63051
1977	57.17724
1978	67.87251
1979	69.80312
1980	67.71856
1981	67.24517
1982	64.62504
1983	69.17065
1984	62.95502
1985	72.23075
1986	69.87581
1987	64.60557
1988	66.74918
1989	62.80569
1990	65.09554
1991	60.55877
1992	48.98885
1993	47.54943
1994	46.29803
1995	55.8514
1996	58.37526
1997	51.67165
1998	59.58028
1999	35.54434
2000	39.02299
2001	45.15205
2002	55.26638
2003	56.60175
2004	56.93593
2005	56.78426
2006	51.5842
2007	57.90544
2008	51.94341
2009	63.34216
2010	60.2527
2011	61.29106
2012	60.75781
2013	62.57964
2014	57.42419
2015	64.7233
2016	68.11936