Year	Percent
1998	93.07914
1999	91.79973
2000	92.1872
2001	90.93529
2002	92.00788
2003	91.8511
2004	92.74997
2005	91.95157
2006	91.86901
2007	91.53509
2008	91.22636
2009	89.97204
2010	90.51369
2011	90.7578
2012	90.48732
2013	89.908
2014	89.39392
2015	88.18186
2016	87.6652
2017	88.23086