Year	Percent
1991	62.82
1992	62.74
1993	62.79
1994	62.94
1995	62.99
1996	63.02
1997	63.07
1998	63.1
1999	63.08
2000	63.14
2001	63.17
2002	63.14
2003	63.9
2004	67.26
2005	67.46
2006	64.97
2007	66.47
2008	66.72
2009	67.23
2010	65.87
2011	66.06
2012	69.44
2013	68.21
2014	66.1
2015	66.47
2016	66.68
2017	67.31
2018	68.02
2019	67.87
2020	64.9