Year	Percent
1996	88.92976
1997	89.209
1998	89.77547
1999	90.27082
2000	90.76281
2001	90.87974
2002	91.26844
2003	91.44566
2004	90.43591
2005	90.92563
2006	91.68678
2007	91.40363
2008	91.99502
2009	91.5808
2010	91.70485
2011	92.11439
2012	92.07293
2013	92.49052
2014	92.61133
2015	92.49006
2016	92.53056
2017	92.61006