Year	%
1971	92.00256
1972	94.03185
1973	94.95018
1974	95.64346
1975	96.41611
1976	96.57841
1977	97.70778
1978	98.08962
1979	98.68589
1980	98.53027
1981	98.51411
1982	98.33893
1983	98.66052
1984	98.54253
1985	98.94061
1986	98.87999
1987	100
1988	100
1989	100
1990	97.57061
1991	99.36784
1994	95.18953
1995	100
1996	99.24024
1999	100
2000	99.5393
2001	99.59848
2002	99.66008
2003	99.15694
2004	99.24305
2005	98.66961
2006	99.34582
2007	99.92328
2008	99.88638
2009	100
2010	99.88257
2011	100
2012	99.78574
2013	99.75424
2014	99.84551
2015	99.85309
2016	99.89696