Year	Percent
1990	80.01
1991	80.31
1992	80.94
1993	80.33
1994	81.36
1995	80.85
1996	81.12
1997	82.04
1998	81.88
1999	81.81
2000	82.28
2001	84.08
2002	85.22
2003	86.2
2004	86.65
2005	86.13
2006	86.55
2007	86.99
2008	86.56
2009	86.63
2010	87.26
2011	87.56
2012	87.87
2013	88.07
2014	88.74
2015	88.21
2016	87.09
2017	87.74
2018	87.45
2019	88.45