Year	Percent
1990	91.95
1991	91.75
1992	91.6
1993	91.45
1994	91.25
1995	91.1
1996	90.95
1997	90.75
1998	90.6
1999	90.4
2000	90.25
2001	90.1
2002	89.9
2003	89.75
2004	89.55
2005	89.4
2006	89.25
2007	89.05
2008	88.9
2009	88.75
2010	88.55
2011	88.4
2012	88.2
2013	88.05
2014	87.9
2015	87.72