Year	Percent
1990	64.1
1991	64.06
1992	64.42
1993	64.35
1994	64.32
1995	64.4
1996	64.34
1997	64.36
1998	64.23
1999	64.19
2000	64.1
2001	64.24
2002	63.9
2003	63.8
2004	65.29
2005	64.51
2006	63.72
2007	62.95
2008	62.19
2009	61.43
2010	60.69
2011	59.94
2012	59.21
2013	58.48
2014	57.75
2015	58.19
2016	58.1
2017	58.05
2018	58
2019	57.89
2020	57.1