Year	Percent
1990	81.03
1991	81.41
1992	81.36
1993	81.06
1994	81.3
1995	81.54
1996	82.14
1997	81.87
1998	81.48
1999	81.77
2000	82.06
2001	82.36
2002	82.7
2003	82.42
2004	82.87
2005	83.86
2006	84
2007	84
2008	84.22
2009	84.03
2010	83.76
2011	84.27
2012	83.86
2013	84.58
2014	85.37
2015	85.2
2016	86.53
2017	87.24
2018	87.42
2019	87.47