Year	Percent
1991	58.98
1992	58.82
1993	58.7
1994	58.74
1995	58.24
1996	58.16
1997	58
1998	57.37
1999	57.05
2000	57.8
2001	59.64
2002	59.97
2003	60.44
2004	60.68
2005	59.67
2006	60.35
2007	61.08
2008	61.1
2009	60.19
2010	60.05
2011	58.23
2012	55.42
2013	52.74
2014	53.07
2015	53.3
2016	53.97
2017	55.4
2018	57.94
2019	59.27
2020	58.89