Year	Percent
1990	89.71
1991	88.57
1992	87.8
1993	87.32
1994	87.16
1995	85.37
1996	85.36
1997	86.9
1998	86.92
1999	87.98
2000	88.15
2001	88.2
2002	88.42
2003	87.92
2004	87.38
2005	87.7
2006	87.81
2007	88.04
2008	88.59
2009	88.22
2010	87.54
2011	87.66
2012	87.3
2013	86.77
2014	86.65
2015	86.63
2016	86.3
2017	86.76
2018	87.75
2019	87.64