Year	Percent
1990	61.15
1991	61.79
1992	63.26
1993	63.5
1994	65.25
1995	66.13
1996	65.91
1997	67.09
1998	66.81
1999	65.84
2000	65.61
2001	65.45
2002	65.57
2003	65.44
2004	65.16
2005	64.31
2006	63.64
2007	62.99
2008	62.2
2009	62
2010	61.74
2011	61.33
2012	61.21
2013	61.21
2014	61.21
2015	61.28
2016	61.32
2017	61.29
2018	61.25
2019	61.2