Year	Percent
1990	58.55
1991	58.64
1992	58.77
1993	58.87
1994	58.94
1995	59.02
1996	59.11
1997	59.22
1998	59.33
1999	59.43
2000	59.53
2001	58.37
2002	58.9
2003	57.8
2004	57.74
2005	57.54
2006	58.77
2007	58.39
2008	58.76
2009	56.56
2010	58.08
2011	59.7
2012	60.49
2013	60.78
2014	61.08
2015	63.73
2016	64.11
2017	64.15
2018	65.71
2019	66.97
2020	61.73