Year	Percent
1995	89.77003
1996	89.70466
1997	90.15154
1998	90.44228
1999	90.48317
2000	90.62344
2001	90.78057
2002	90.71745
2003	91.11287
2004	90.89901
2005	90.4371
2006	90.46499
2007	90.60053
2008	90.77175
2009	90.46306
2010	90.1566
2011	90.58521
2012	90.6096
2013	90.38215
2014	90.65237
2015	90.82238
2016	91.00859
2017	91.13944