Year	% net
1971	93.44517
1972	92.58401
1973	91.88096
1974	91.6389
1975	92.61165
1976	96.26375
1977	96.22785
1978	94.70958
1979	90.07082
1980	86.63927
1981	92.41886
1982	93.03454
1983	94.0754
1984	92.65937
1985	93.07886
1986	91.37001
1987	93.03525
1988	93.99259
1989	92.3568
1990	91.88367
1991	89.6875
1992	89.23438
1993	88.53352
1996	88.73928
1997	88.83932
1999	93.93764
2000	93.81147
2001	92.9984
2002	90.36456
2003	90.54868
2004	91.31061
2005	88.34703
2008	94.05619
2009	94.87768
2010	94.83918