Year	Percent
1990	70.23
1991	70.18
1992	70.25
1993	70.38
1994	70.44
1995	70.4
1996	70.1
1997	69.87
1998	69.75
1999	71.36
2000	70.46
2001	69.75
2002	70.05
2003	70.14
2004	70.06
2005	69.83
2006	69.89
2007	69.25
2008	68.55
2009	67.91
2010	67.33
2011	67.05
2012	66.82
2013	66.84
2014	66.74
2015	66.72
2016	66.69
2017	67.05
2018	67.27
2019	67.31
2020	67.26