Year	Percent
1991	63.8
1992	64.08
1993	63.3
1994	63.52
1995	63.42
1996	63.3
1997	62.97
1998	62.86
1999	62.59
2000	63.15
2001	62.33
2002	60.88
2003	60.45
2004	60.29
2005	58.83
2006	59.21
2007	60.94
2008	61.84
2009	62.59
2010	63.42
2011	63.81
2012	64.71
2013	64.14
2014	64.11
2015	63.49
2016	63.33
2017	64.21
2018	64.47
2019	65.54
2020	63.72