Year	%
1971	94.29668
1972	95.95765
1973	96.74479
1974	97.19646
1975	97.99977
1976	97.89369
1977	98.72519
1978	99.06099
1979	99.3225
1980	99.28311
1981	99.27574
1982	99.18871
1983	99.34742
1984	99.28792
1985	99.48355
1986	99.4532
1987	97.59747
1988	98.21497
1989	97.564
1990	98.11502
1991	99.69248
1994	97.60877
1995	99.81947
1996	99.63163
1999	96.70295
2000	99.77574
2001	99.805
2002	99.83511
2003	99.59101
2004	99.63237
2005	99.35534
2006	99.68376
2007	99.9629
2008	99.94487
2009	99.94359
2010	99.94311
2011	99.81212
2012	99.89623
2013	99.88062
2014	99.92509
2015	99.92865
2016	99.95024