Year	Percent
1983	91.15415
1985	91.69018
1987	90.30288
1988	90.71734
1989	90.66934
1990	90.07438
1991	90.8471
1992	90.51541
1993	90.33024
1994	89.63838
1995	89.15153
1996	89.55142
1997	89.40974
1998	89.89943
1999	89.91805
2000	89.83379
2001	89.61596
2002	89.42158
2003	89.76174
2004	89.15245
2005	88.76471
2006	88.37835
2007	87.95118
2008	87.8574
2009	87.48276
2010	86.1701
2011	85.76638
2012	85.56448
2013	84.69483
2014	84.25377
2015	84.11465
2016	84.06185
2017	84.11674