Year	Percent
1990	92.49
1991	92.16
1992	91.53
1993	90.61
1994	89.67
1995	88.42
1996	88.49
1997	88.26
1998	87.99
1999	87.68
2000	87.32
2001	86.98
2002	86.65
2003	86.33
2004	86.04
2005	85.79
2006	85.61
2007	85.46
2008	85.34
2009	85.22
2010	85.08
2011	84.95
2012	84.79
2013	84.61
2014	84.4
2015	84.35
2016	84.28
2017	84.24
2018	84.18
2019	84.08