Year	Percent
1991	64.81
1992	61.72
1993	57.87
1994	57.14
1995	58.03
1996	57.49
1997	56.57
1998	57.19
1999	58.2
2000	58.96
2001	59.64
2002	59.39
2003	59.06
2004	58.17
2005	58.16
2006	58.82
2007	59.71
2008	59.82
2009	58
2010	57.7
2011	58.45
2012	58.4
2013	58.74
2014	58.89
2015	59.24
2016	59.59
2017	60
2018	60.29
2019	60.03
2020	58.79