Year	Percent
1990	75.4
1991	73.02
1992	70.41
1993	70.8
1994	70.23
1995	69.08
1996	69.05
1997	69.13
1998	72.3
1999	70.05
2000	70.49
2001	70.38
2002	70.29
2003	70.19
2004	70.09
2005	69.98
2006	69.9
2007	69.81
2008	69.72
2009	69.63
2010	68.71
2011	68.67
2012	67.59
2013	69.5
2014	69.09
2015	69.67
2016	70.26
2017	70.21
2018	68.66
2019	68.56