Year	Percent
1971	0.55802
1972	0.56751
1973	0.54619
1974	0.56141
1975	0.55699
1976	0.56852
1977	0.57641
1978	0.58104
1984	0.62155
1985	0.62367
1988	0.63399
1989	0.65694
1990	0.6404
1991	0.65849
2001	0.70149
2011	0.88618
2012	0.9431
2013	0.9554
2015	0.9682
2016	0.97845