Year	Percent
1990	94.25
1991	94.26
1992	94.27
1993	94.28
1994	94.27
1995	94.26
1996	94.25
1997	94.23
1998	94.2
1999	94.17
2000	94.14
2001	94.11
2002	94.07
2003	94.03
2004	93.98
2005	93.94
2006	93.9
2007	93.86
2008	93.82
2009	93.77
2010	93.73
2011	93.71
2012	93.69
2013	93.67
2014	93.65
2015	93.62
2016	93.59
2017	93.56
2018	93.53
2019	93.51