Year	Percent
1991	62.13
1992	62.3
1993	62.53
1994	62.78
1995	63.06
1996	63.14
1997	63.29
1998	63.55
1999	63.89
2000	64.24
2001	63.94
2002	63.54
2003	63.27
2004	63.12
2005	63.02
2006	62.6
2007	62.23
2008	62.03
2009	62.1
2010	62.1
2011	62.02
2012	61.89
2013	61.71
2014	61.44
2015	60.8
2016	60.11
2017	59.36
2018	60.79
2019	60.24
2020	58.57