Year	Percent
1971	0.82893
1972	0.8358
1974	0.84059
1988	0.92347
1989	0.94595
1990	0.95537
2005	0.95652
2006	0.95864
2007	0.96357
2008	0.96397
2009	0.96801
2011	0.97112
2012	0.97605
2014	0.98986
2015	0.99375
2016	0.99674