Year	%
1971	96.47764
1972	97.7981
1973	98.46055
1974	98.6792
1975	99.50886
1976	99.14734
1977	99.69815
1978	99.9869
1979	99.92607
1980	100
1981	100
1982	100
1983	100
1984	100
1985	100
1986	100
1987	95.33693
1988	96.51849
1989	95.24373
1990	98.63199
1991	100
1994	100
1995	99.65113
1996	100
1999	93.60468
2000	100
2001	100
2002	100
2003	100
2004	100
2005	100
2006	100
2007	100
2008	100
2009	99.891
2010	100
2011	99.63696
2012	100
2013	100
2014	100
2015	100
2016	100