Year	Percent
1990	68.83
1991	67.43
1992	68.23
1993	68.84
1994	69.31
1995	69.98
1996	69.16
1997	69.07
1998	68.85
1999	68.6
2000	68.34
2001	68.35
2002	68.38
2003	68.41
2004	69.01
2005	68.89
2006	68.68
2007	68.44
2008	68.15
2009	67.83
2010	67.37
2011	67.26
2012	66.19
2013	66.9
2014	64.84
2015	65.35
2016	66.05
2017	65.81
2018	65.56
2019	65.3
2020	61.65