Year	Percent
1990	65.68
1991	65.85
1992	65.9
1993	65.83
1994	65.78
1995	65.78
1996	65.59
1997	65.52
1998	65.46
1999	65.32
2000	65.1
2001	65.06
2002	65.03
2003	64.99
2004	64.95
2005	64.91
2006	64.8
2007	64.65
2008	64.43
2009	64.11
2010	63.82
2011	63.25
2012	62.62
2013	62.09
2014	61.64
2015	61.22
2016	60.93
2017	60.68
2018	60.48
2019	60.27
2020	57.61