Year	Percent
1989	87.8
1990	88.9
1991	89.3
1992	90.9
1993	93.3
1994	93.4
1995	94.1
1996	95
1997	95.6
1998	96.6
1999	97
2000	97.7
2001	97.6
2002	98.2
2003	99
2004	99
2005	99.1
2006	97.8
2007	99.6
2008	99.7
2009	99.8
2010	99.9
2011	91.2
2012	99.9
2013	99.9
2014	99.9
2015	99.9
2016	99.9