Year	Percent
1991	71.41
1992	71.4
1993	70.96
1994	70.55
1995	70.11
1996	69.69
1997	69.25
1998	68.76
1999	67.28
2000	66.99
2001	67.3
2002	67.49
2003	67.66
2004	67.83
2005	67.97
2006	68.09
2007	67.76
2008	67.39
2009	66.85
2010	66.4
2011	65.84
2012	65.24
2013	64.61
2014	64.01
2015	63.39
2016	64.31
2017	65.08
2018	65.07
2019	65.02
2020	63.21