Year	Percent
1990	84.51
1991	84.84
1992	84.9
1993	85.26
1994	84.74
1995	84.04
1996	83.65
1997	82.76
1998	82.82
1999	82.53
2000	82.86
2001	82.36
2002	81.8
2003	81.63
2004	81.85
2005	82.63
2006	81.82
2007	81.79
2008	82.52
2009	83.41
2010	84.15
2011	84.22
2012	84.63
2013	84.65
2014	85.14
2015	85.21
2016	85
2017	85.04
2018	85.3
2019	85.42