Year	%
1975	99.1611
1976	99.97539
1977	99.61541
1978	99.63427
1979	100
1980	99.93276
1981	99.70953
1982	99.82449
1983	99.8458
1984	100
1985	99.70823
1986	99.78579
1987	99.06641
1988	99.88721
1989	100
1996	98.8251
1997	98.78476
1998	98.45619
1999	98.69107
2000	99.98433
2001	100
2002	99.72574
2003	99.67678
2004	99.30143
2005	99.20615
2006	99.2233
2007	99.67891
2008	99.63892
2009	100
2010	99.81112
2012	99.46663
2013	99.64102
2014	99.61397
2015	99.75976
2016	98.97728