Year	Percent
1990	81.33536
1991	80.51512
1992	75.43424
1993	82.8225
1994	80.01806
1995	80.78176
1996	83.46019
1997	84.66899
1998	86.11111
1999	80.61633
2006	84.86472
2007	86.78215
2009	77.53155
2010	77.99483
2011	79.60671
2012	81.83322
2013	83.55335
2014	85.60371
2015	85.64822
2016	85.5915
2017	85.05055