Year	Percent
1990	87.07
1991	87.27
1992	87.84
1993	88.37
1994	88.72
1995	88.83
1996	88.83
1997	88.2
1998	88.04
1999	87.94
2000	87.78
2001	87.76
2002	87.73
2003	88.21
2004	88.21
2005	88.17
2006	88.1
2007	88.03
2008	87.99
2009	87.99
2010	88
2011	87.98
2012	87.98
2013	87.99
2014	88.11
2015	88.25
2016	89.23
2017	89.34
2018	89.47
2019	89.64