Year	Percent
1990	91.35
1991	91.52
1992	91.7
1993	91.97
1994	92.31
1995	92.52
1996	92.49
1997	92.38
1998	92.31
1999	92.16
2000	91.92
2001	91.7
2002	91.57
2003	91.5
2004	91.3
2005	91.79
2006	92.25
2007	92.68
2008	93.09
2009	93.02
2010	93.56
2011	93.66
2012	93.76
2013	93.84
2014	93.26
2015	92.61
2016	92.08
2017	91.54
2018	91.62
2019	91.71