Year	Percent
1990	84.22
1991	84.26
1992	84.27
1993	84.27
1994	84.17
1995	84.03
1996	83.9
1997	83.73
1998	83.53
1999	83.31
2000	83.1
2001	82.96
2002	82.82
2003	82.69
2004	82.56
2005	82.47
2006	82.47
2007	82.46
2008	80.68
2009	78.78
2010	76.77
2011	76.86
2012	76.95
2013	77.02
2014	77.06
2015	77.07
2016	77.07
2017	77.05
2018	76.99
2019	76.9