Year	Percent
1991	66.28
1992	65.24
1993	66.1
1994	64.89
1995	64.71
1996	60.5
1997	59.13
1998	56.54
1999	56.52
2000	56.6
2001	58.59
2002	55.88
2003	57.83
2004	56.14
2005	55.26
2006	55.58
2007	55.96
2008	53.19
2009	51.54
2010	52.92
2011	54.1
2012	54.85
2013	54.59
2014	56.58
2015	57.83
2016	57.07
2017	57.44
2018	56.16
2019	56.26
2020	56.17