Year	Percent
1990	66.01
1991	65.99
1992	66.15
1993	66.33
1994	66.4
1995	66.58
1996	66.69
1997	66.86
1998	67.01
1999	67.09
2000	66.06
2001	64.99
2002	64.7
2003	64.42
2004	64.14
2005	63.85
2006	62.29
2007	61.33
2008	62.09
2009	63.19
2010	64.35
2011	62.19
2012	61.25
2013	65.15
2014	66.6
2015	66.57
2016	66.16
2017	66.99
2018	68.76
2019	68.97
2020	59.97