Year	Percent
1991	56.05
1992	57.05
1993	57.22
1994	57
1995	57.82
1996	64.84
1997	64.69
1998	63.12
1999	61.63
2000	60.9
2001	61.72
2002	59.92
2003	58.61
2004	60.14
2005	61.75
2006	63.65
2007	66.53
2008	67.8
2009	67.91
2010	68.8
2011	69.46
2012	69.55
2013	69.78
2014	70.58
2015	70.31
2016	69.44
2017	68.98
2018	69.1
2019	68.62
2020	69.17