Year	Percent
1985	87.10688
1986	88.16752
1987	86.87842
1988	86.13377
1989	86.44562
1990	85.90597
1991	86.5081
1992	85.75952
1993	85.47626
1994	85.80552
1995	85.90214
1996	86.72569
1997	86.56128
1998	85.82441
1999	86.49374
2000	86.26878
2001	86.46571
2002	86.69901
2003	86.72716
2004	86.38242
2005	86.95527
2006	87.43166
2007	87.35659
2008	86.86333
2009	86.38975
2010	86.65569
2011	86.954
2012	87.10479
2013	86.78846
2014	86.82324
2015	87.11198
2016	87.31996
2017	87.84104