Year	Percent
1990	86.08
1991	86.06
1992	86.07
1993	86.1
1994	86.16
1995	86.22
1996	86.17
1997	86.13
1998	86.09
1999	86.05
2000	85.79
2001	85.57
2002	85.34
2003	85.08
2004	84.81
2005	84.51
2006	84.23
2007	83.94
2008	83.63
2009	83.44
2010	83.23
2011	82.98
2012	82.73
2013	82.49
2014	82.26
2015	82.03
2016	82.11
2017	82.2
2018	82.32
2019	82.45
2020	77.22