Year	Percent
1990	85.87
1991	85.42
1992	85.28
1993	84.92
1994	85.14
1995	86.28
1996	86.5
1997	87.76
1998	88.19
1999	87.91
2000	87.68
2001	87.47
2002	87.69
2003	86.07
2004	86.04
2005	86.45
2006	86.93
2007	87.43
2008	88.46
2009	88.08
2010	87.29
2011	87.02
2012	86.84
2013	86.58
2014	86.77
2015	86.53
2016	86.37
2017	85.65
2018	86.29
2019	86.29