Year	Percent
1990	67.57
1991	67.57
1992	67.74
1993	67.93
1994	68.01
1995	68.21
1996	68.33
1997	68.51
1998	68.68
1999	68.78
2000	67.86
2001	66.88
2002	66.54
2003	66.2
2004	65.85
2005	65.5
2006	63.94
2007	62.95
2008	63.71
2009	64.68
2010	66.01
2011	63.75
2012	62.97
2013	66.86
2014	68.49
2015	68.43
2016	68.27
2017	68.74
2018	70.77
2019	71.05