Year	Percent
1990	89.05
1991	89.08
1992	89.31
1993	89.44
1994	89.47
1995	89.39
1996	88.73
1997	88.29
1998	88.38
1999	87.02
2000	88
2001	85.48
2002	84.2
2003	85.26
2004	85.76
2005	85.79
2006	89.02
2007	88.48
2008	88.17
2009	87.79
2010	88.27
2011	88.37
2012	87.77
2013	87.6
2014	87.07
2015	87.86
2016	87.8
2017	88.58
2018	88.31
2019	87.75