Year	Percent
1965	79.17608
1966	75.48274
1967	59.5721
1968	57.80773
1969	59.31178
1970	80.66848
1971	75.3576
1972	75.36449
1973	89.94555
1974	96.2548
1975	96.24706
1976	100.31383
1977	103.28147
1978	96.93122
1979	95.39037
1980	91.46063
1981	91.87972
1982	88.72935
1983	90.45286
1984	85.35164
1985	76.91224
1986	73.16931
1987	61.50927
1988	66.71025
1989	73.09524
1990	59.76847
1991	53.13026
1992	69.6526
1993	72.19296
1994	72.26598
1995	75.6665
1996	73.86172
1997	74.02543
1998	70.05262
1999	65.66987
2000	70.51627
2001	68.99245
2002	63.90028
2003	66.13983
2004	69.3631
2005	75.08814
2006	72.13996
2007	73.31895
2008	76.1871
2009	69.78303
2010	80.27501
2011	82.57787
2012	83.97249
2013	82.91295
2014	81.86119
2015	74.26693
2016	69.44645
2017	74.30796