Year	% net
1970	79.76394
1972	70.376
1973	81.46099
1975	78.96045
1976	80.08288
1977	81.03834
1978	82.71852
1979	83.98334
1980	86.10981
1981	87.98265
1983	88.35086
1984	87.90906
1985	87.79023
1986	86.71118
1987	87.43822
1988	89.01053
1989	90.83886
1990	92.56517
1991	94.48361
1992	85.7437
1993	95.5992
1994	90.99687
1995	90.71599
1996	93.89767
1999	95.51996
2000	96.74098
2001	96.50642
2002	94.55333
2003	93.86873
2004	93.30224
2005	93.95193
2006	92.30766
2007	90.56343
2008	89.02356
2009	87.97956
2010	87.9171
2011	87.7094
2012	87.19751