Year	Percent
1990	63.51
1991	63.57
1992	63.62
1993	63.68
1994	63.74
1995	63.77
1996	63.68
1997	63.59
1998	63.54
1999	63.52
2000	63.52
2001	63.52
2002	63.5
2003	63.42
2004	63.26
2005	63.76
2006	63.6
2007	62.74
2008	62.75
2009	62.8
2010	63.64
2011	63.1
2012	63.44
2013	64.86
2014	65.43
2015	66.24
2016	65.81
2017	66.34
2018	66.2
2019	66.17