Year	Percent
1991	54.25
1992	54.84
1993	54.71
1994	56.47
1995	56.49
1996	55.44
1997	55.2
1998	55.25
1999	55.87
2000	55.77
2001	55.63
2002	55.98
2003	55.95
2004	53.5
2005	54.84
2006	55.43
2007	56.5
2008	57.19
2009	56.8
2010	57.07
2011	57.28
2012	57.36
2013	57.21
2014	56.78
2015	56.66
2016	56.87
2017	57.19
2018	57.79
2019	58.05
2020	56.45