Year	%
1971	97.23924
1972	97.18699
1973	97.15886
1974	97.65859
1975	97.91825
1976	97.82523
1977	97.841
1978	97.96882
1979	98.06853
1980	98.19455
1981	98.20873
1982	98.02982
1983	97.51693
1984	97.37717
1985	97.37005
1986	97.34402
1987	97.34035
1988	97.20866
1989	97.27358
1990	97.90317
1991	98.33156
1992	100
1993	99.19963
1994	96.28323
1995	99.18489
1996	100
1997	97.37488
1998	100
2000	100
2001	100
2002	100
2003	100
2004	100
2005	100
2006	100
2008	99.36142
2009	99.0431
2010	99.18259
2012	99.29776
2013	99.37275
2014	99.46747
2015	99.52425
2016	99.7691