Year	Percent
1990	83.29
1991	83.11
1992	82.7
1993	82.67
1994	82.44
1995	82.27
1996	82.41
1997	82.7
1998	82.86
1999	83.12
2000	83.98
2001	84.51
2002	84.79
2003	84.74
2004	84.72
2005	84.65
2006	84.54
2007	84.4
2008	84.26
2009	84.56
2010	84.44
2011	84.06
2012	83.97
2013	83.94
2014	83.94
2015	83.93
2016	83.91
2017	83.88
2018	83.84
2019	83.84
2020	83.83