Year	Percent
1990	88.28
1991	88.29
1992	88.33
1993	88.4
1994	88.48
1995	88.57
1996	88.53
1997	88.49
1998	88.45
1999	88.43
2000	88.13
2001	87.89
2002	87.65
2003	87.38
2004	87.1
2005	86.78
2006	86.47
2007	86.15
2008	85.81
2009	85.67
2010	85.52
2011	85.34
2012	85.2
2013	85.09
2014	84.99
2015	84.89
2016	85.1
2017	85.3
2018	85.48
2019	85.66