Year	Percent
1990	63.93
1991	64.27
1992	64.49
1993	64.71
1994	65.06
1995	65.28
1996	65.42
1997	65.64
1998	68.16
1999	67.85
2000	67.52
2001	67.17
2002	66.8
2003	66.41
2004	68.75
2005	68.17
2006	69.47
2007	68
2008	68.14
2009	66.22
2010	65.11
2011	64.34
2012	64.94
2013	64.3
2014	64.07
2015	66.48
2016	68.41
2017	69.07
2018	68.03
2019	67.83
2020	62.6