Year	Percent
1998	95.9145
1999	95.34719
2000	95.28262
2001	94.80837
2002	95.25181
2003	93.87148
2004	92.27102
2005	92.33374
2006	91.84653
2007	91.81253
2008	91.89143
2009	90.29288
2010	90.64798
2011	90.22714
2012	90.03036
2013	90.24555
2014	90.08829
2015	89.68727
2016	89.24386
2017	89.56007