Year	%
1973	100
1974	100
1976	84.64369
1977	99.77942
1978	99.06165
1979	100
1981	100
1982	100
1983	100
1984	99.12131
1994	99.4314
1998	93.99088
1999	98.05069
2000	99.51688
2001	99.58184
2002	100
2003	98.30212
2004	98.10134
2009	99.54359
2011	100
2012	99.74222
2015	99.3434
2016	96.8126
2017	98.99229