Year	Percent
1990	87.23
1991	87.33
1992	87.6
1993	88.17
1994	89.39
1995	90.15
1996	89
1997	87.63
1998	86.05
1999	84.28
2000	85.52
2001	84.89
2002	84.16
2003	83.77
2004	82.78
2005	82.28
2006	82.2
2007	82.14
2008	82.09
2009	82.04
2010	82.42
2011	82.59
2012	82.69
2013	83.44
2014	82.16
2015	82.75
2016	82.39
2017	82.3
2018	82.3
2019	82.32