Year	Percent
1991	55.47
1992	55.84
1993	56.12
1994	56.3
1995	56.44
1996	56.84
1997	57.1
1998	57.26
1999	57.35
2000	57.42
2001	57.68
2002	57.82
2003	57.86
2004	57.81
2005	57.68
2006	57.79
2007	57.74
2008	57.54
2009	57.1
2010	56.68
2011	56.46
2012	56.12
2013	55.7
2014	55.25
2015	54.72
2016	54.34
2017	53.9
2018	53.39
2019	52.8