Year	Percent
1990	67.52
1991	66.98
1992	65.46
1993	63.82
1994	63.2
1995	63.7
1996	63.56
1997	63.1
1998	62.8
1999	62.99
2000	62.37
2001	62.6
2002	62.49
2003	62.53
2004	62.34
2005	62.87
2006	63.29
2007	63.63
2008	63.79
2009	63.29
2010	63.13
2011	63.4
2012	63.46
2013	63.89
2014	63.98
2015	64
2016	64.07
2017	64.32
2018	64.39
2019	64.43
2020	64.22