Year	Percent
1990	65.55
1991	69.01
1992	69.52
1993	68.09
1994	66.74
1995	64.86
1996	63.92
1997	65.3
1998	64.43
1999	63.16
2000	62.44
2001	61.32
2002	60.56
2003	59.53
2004	58.48
2005	57.46
2006	56.58
2007	55.79
2008	55.04
2009	54.52
2010	54.27
2011	60.13
2012	57.06
2013	53.12
2014	53.3
2015	55.61
2016	56.61
2017	57.1
2018	59.33
2019	60.32
2020	59.72