Year	Percent
1991	56.32
1992	56.25
1993	55.81
1994	57.95
1995	57.29
1996	55.96
1997	55.58
1998	57.81
1999	57.83
2000	57.16
2001	56.66
2002	56.88
2003	57.92
2004	56.81
2005	56.51
2006	57.33
2007	57.89
2008	58.11
2009	57.09
2010	57
2011	57.2
2012	58.11
2013	58.56
2014	57.09
2015	56.49
2016	56.89
2017	56.6
2018	56.57
2019	56.78
2020	48.77