Year	Percent
1991	67.75
1992	67.66
1993	67.77
1994	67.97
1995	68.2
1996	68.38
1997	68.63
1998	68.72
1999	68.72
2000	68.75
2001	69.15
2002	69.5
2003	69.87
2004	70.25
2005	70.63
2006	71.03
2007	69.98
2008	70.31
2009	70.05
2010	70.18
2011	70.25
2012	67.52
2013	67.64
2014	69.84
2015	64.99
2016	65.32
2017	66.54
2018	69.42
2019	69.61
2020	62.92