Year	Percent
1996	81.15832
1997	81.42163
1998	82.91451
1999	83.3264
2000	83.3231
2001	83.92833
2002	85.09848
2003	84.67482
2004	83.59012
2005	84.39542
2006	85.63443
2007	86.00317
2008	85.84382
2009	85.70549
2010	85.97187
2011	85.81479
2012	86.91449
2013	87.47315
2014	87.23348
2015	87.92006
2016	88.39426
2017	89.19674