Year	%
1971	80.45302
1972	77.48653
1975	82.68081
1976	85.10075
1977	90.29984
1978	94.0871
1979	96.4725
1981	98.77851
1982	98.13558
1983	98.59988
1984	98.89591
1985	99.14486
1986	99.15114
1987	99.18392
1994	99.55602
1997	99.78142
1998	100
1999	99.5969
2000	99.37204
2001	99.33426
2002	99.29503
2003	99.11818
2004	99.13775
2005	99.23678
2006	99.18585
2007	99.91071
2008	100
2010	99.96816
2012	99.95227
2013	99.79813
2014	99.75648
2015	99.79796
2016	99.77094