Year	% net
1970	74.65225
1971	82.85382
1972	85.37972
1973	87.3349
1975	88.78248
1976	88.80246
1978	90.76377
1979	89.59459
1980	88.25426
1981	86.96386
1982	85.98761
1983	84.72215
1984	84.36712
1985	85.05903
1986	84.56442
1987	85.64312
1988	85.05094
1989	86.71608
1990	86.82492
1999	92.78902
2000	94.67437
2001	95.81135
2002	97.73026
2005	96.96014
2006	97.61528
2008	96.30659
2009	93.44757
2010	94.89117
2011	94.18456
2012	93.5648
2013	92.73396
2014	90.46746
2015	87.08955
2017	85.90651