Year	Percent
1990	83.94
1991	84.46
1992	84.91
1993	85.47
1994	85.95
1995	86.16
1996	86.66
1997	86.23
1998	86.4
1999	86.45
2000	86.4
2001	86.14
2002	86.17
2003	87.17
2004	87.22
2005	87.34
2006	87.63
2007	87.99
2008	88.54
2009	88.63
2010	88.72
2011	88.27
2012	88.21
2013	88.33
2014	87.88
2015	87.51
2016	87.54
2017	87.48
2018	87.64
2019	87.44