Year	Percent
1990	92.82
1991	92.87
1992	92.95
1993	93.03
1994	93.13
1995	93.21
1996	93.21
1997	93.2
1998	93.18
1999	93.17
2000	92.99
2001	92.84
2002	92.68
2003	92.51
2004	92.34
2005	92.17
2006	92
2007	91.82
2008	91.62
2009	91.64
2010	91.66
2011	91.63
2012	91.64
2013	91.66
2014	91.68
2015	91.7
2016	91.85
2017	91.98
2018	92.09
2019	92.18