Year	Percent
1990	92.8
1995	95.1
1998	96.2
2000	96.6
2001	96.8
2002	97
2003	97.6
2004	98
2005	98.1
2006	98.4
2007	98.6
2008	98.6
2009	98.6
2010	98.6
2011	98.6
2012	98.7
2013	98.8
2014	98.97
2015	99.4