Year	%
1971	58.56582
1972	58.86915
1975	67.49127
1976	71.39108
1977	78.50548
1978	86.35386
1979	91.63086
1981	95.98272
1982	95.79526
1983	97.34334
1984	97.98188
1985	98.5204
1986	98.77613
1987	98.68974
1994	99.22676
1997	99.76554
1998	99.78867
1999	99.65371
2000	99.30916
2001	99.28177
2002	99.45682
2003	98.22203
2004	98.68869
2005	98.62376
2006	98.49254
2007	99.93443
2008	99.98423
2010	100
2012	99.6269
2013	99.56331
2014	99.50979
2015	99.49422
2016	99.50415