Year	%
1986	98.39382
1987	98.15296
1988	98.56063
1989	97.77379
1990	98.26912
1991	97.08025
1992	98.83982
1993	98.55885
1997	100
1998	99.8196
1999	99.55731
2000	100
2001	100
2002	100
2003	99.86073
2004	100
2005	99.76573
2006	99.83161
2007	100
2008	99.76389
2009	99.88244
2010	100
2011	100
2012	99.86796
2013	100
2014	99.7149
2015	99.97783
2016	100