Year	Percent
1971	0.55323
1972	0.5749
1973	0.5907
1974	0.61875
1975	0.60875
1976	0.61299
1977	0.62089
1978	0.61912
1979	0.62154
1980	0.63332
1981	0.64552
1982	0.65493
1983	0.66795
1984	0.68161
1985	0.6034
1986	0.60613
1987	0.70488
1988	0.67914
1992	0.69847
1993	0.70658
1994	0.67292
1995	0.6702
2007	0.73986
2008	0.76395
2009	0.77433
2010	0.78781
2011	0.78898
2012	0.80111
2013	0.82777
2014	0.82886
2015	0.88949