Year	Percent
1990	72.18
1991	71.79
1992	71.42
1993	71.03
1994	70.63
1995	70.21
1996	70.06
1997	69.96
1998	69.91
1999	69.91
2000	69.96
2001	70.01
2002	70.13
2003	70.29
2004	70.47
2005	70.66
2006	70.58
2007	70.51
2008	70.45
2009	70.41
2010	68.29
2011	66.35
2012	63.78
2013	64.27
2014	62.6
2015	65.94
2016	66.27
2017	66.61
2018	66.95
2019	67.26
2020	65.29