Year	Percent
1991	56.85
1992	57.4
1993	57.98
1994	57.18
1995	55.4
1996	56.39
1997	58.48
1998	58.58
1999	58.53
2000	58.32
2001	57.74
2002	57.08
2003	57.15
2004	57.37
2005	58.42
2006	59.12
2007	59.14
2008	58.68
2009	57.68
2010	57.5
2011	57.61
2012	58.43
2013	58.23
2014	57.72
2015	58.14
2016	58.33
2017	58.41
2018	58.71
2019	59.28
2020	53.79