Year	Percent
1988	83.45882
1989	84.21821
1991	86.81821
1992	90.33934
1993	89.17018
1996	84.87356
1997	83.93701
1999	83.65428
2000	84.89198
2001	86.34824
2002	92.54143
2003	90.03532
2004	90.4824
2005	92.66423
2006	96.52683
2007	97.75894
2008	94.57984
2009	94.69256
2010	93.35103
2011	94.96644
2012	96.35332
2013	96.39057
2014	96.70596
2015	95.42972
2016	92.36462