Year	%
1973	84.70978
1974	93.13036
1975	85.64279
1976	92.46624
1977	81.94124
1978	82.84999
1979	89.85294
1980	83.94708
1981	82.42197
1982	81.09666
1983	83.50305
1984	84.84018
1985	82.00033
1986	85.92725
1987	80.3088
1988	89.34662
1989	90.70069
1990	91.02161
1991	88.7684
1992	83.85969
1993	81.60682
1995	86.66155
1998	87.92336
1999	83.91416
2000	87.61909
2001	85.68674
2004	82.14564
2005	83.63632
2006	84.89327
2007	89.23697
2008	84.13884
2009	89.68796
2010	89.04605
2011	86.39633