Year	Percent
1990	56.28
1991	56.53
1992	55.19
1993	55.81
1994	56.46
1995	56.61
1996	57.41
1997	58.1
1998	60.07
1999	61.63
2000	62.53
2001	62.44
2002	62.58
2003	62.79
2004	63.07
2005	65.11
2006	65.86
2007	66.45
2008	65.82
2009	64.2
2010	62.95
2011	62.33
2012	62.04
2013	62.39
2014	62.18
2015	62.15
2016	62.4
2017	62.2
2018	62.36
2019	62.45
2020	61.38