Year	Percent
1990	56.52
1991	56.93
1992	57.24
1993	57.46
1994	58.13
1995	58.44
1996	58.98
1997	60.25
1998	61
1999	61.77
2000	62.84
2001	63.47
2002	64.09
2003	64.08
2004	64.27
2005	62.92
2006	63.11
2007	64.15
2008	64.93
2009	65.07
2010	64.43
2011	64.13
2012	64.59
2013	64.5
2014	64.01
2015	64.07
2016	63.71
2017	63.58
2018	63.84
2019	64.25
2020	63.85