Year	Percent
1990	91.17
1991	90.98
1992	90.77
1993	90.04
1994	87.36
1995	87.08
1996	87.58
1997	87.34
1998	87.55
1999	88.28
2000	88.03
2001	87.58
2002	88.21
2003	87.85
2004	88.13
2005	88.13
2006	88.9
2007	88.87
2008	89.33
2009	88.83
2010	88.42
2011	87.81
2012	87.34
2013	86.98
2014	86.43
2015	86.4
2016	86.06
2017	85.83
2018	86.13
2019	86.49