Year	%
1971	70.10419
1972	68.72418
1975	75.39825
1976	78.52083
1977	84.58983
1978	90.37367
1979	94.13081
1981	97.42432
1982	96.99718
1983	97.99083
1984	98.45282
1985	98.84162
1986	98.96872
1987	98.94397
1994	99.39585
1997	99.77383
1998	99.89887
1999	99.62402
2000	99.34231
2001	99.30961
2002	99.37129
2003	98.69438
2004	98.92714
2005	98.95133
2006	98.86288
2007	99.92188
2008	99.99253
2010	99.98333
2012	99.79734
2013	99.68585
2014	99.639
2015	99.65236
2016	99.6427