Year	Percent
1990	87.62
1991	87.62
1992	87.61
1993	87.57
1994	87.52
1995	87.44
1996	87.41
1997	87.36
1998	87.3
1999	87.23
2000	87.18
2001	87.14
2002	87.47
2003	87.78
2004	88.08
2005	88.35
2006	88.6
2007	88.18
2008	87.71
2009	87.2
2010	86.65
2011	86.05
2012	85.39
2013	84.67
2014	83.87
2015	83.84
2016	83.76
2017	83.67
2018	83.55
2019	83.42
2020	83.16