Year	%
1971	98.93899
1972	99.20191
1973	99.22075
1974	99.36977
1975	99.40962
1976	98.81441
1977	99.31614
1978	97.86037
1979	98.86146
1980	99.04887
1981	98.68209
1982	98.73583
1983	98.50474
1984	98.56432
1985	98.94395
1986	99.79759
1987	98.71651
1988	99.28481
1989	93.54264
1990	98.30983
1991	98.27283
1992	96.68307
1993	95.30895
1994	98.59691
1995	99.41222
1996	97.66742
1998	98.5555
2000	99.33849
2001	98.28265
2002	98.22457
2003	98.29525
2004	98.33621
2005	98.32853
2006	97.72001
2007	97.31275
2008	97.91639
2009	98.80542
2010	98.66867
2011	99.05417
2012	99.29677
2013	99.60124
2014	99.2541
2015	98.70297
2016	99.33268