Year	Percent
1991	63.11
1992	62.91
1993	63.32
1994	63.72
1995	64.01
1996	63.84
1997	63.72
1998	63.57
1999	62.88
2000	62.22
2001	61.55
2002	60.83
2003	60.13
2004	59.43
2005	58.75
2006	58.12
2007	57.48
2008	56.8
2009	55.9
2010	55.14
2011	54.42
2012	53.7
2013	54.83
2014	54.6
2015	54.33
2016	54.05
2017	52.04
2018	52.01
2019	51.99
2020	50.97