Year	% net
1970	61.05089
1971	61.03959
1972	63.46915
1973	64.95375
1974	65.98382
1975	68.57909
1976	70.98959
1977	72.52575
1978	73.7533
1979	73.03892
1980	75.49762
1981	75.14665
1982	76.42576
1983	77.20048
1984	78.6007
1985	79.05305
1986	79.96433
1987	80.95694
1988	81.73795
1989	81.74074
1990	83.76526
1991	84.69624
1992	82.25756
1993	82.45526
1994	84.07495
1995	82.75021
1996	84.54343
1997	84.38655
1999	83.55563
2000	84.39146
2001	86.9831
2002	88.96094
2003	89.31743
2004	90.02412
2005	89.45346
2006	89.29567
2007	90.55776
2008	91.13454
2009	91.74741
2010	92.74378
2011	92.81914
2012	94.2456
2013	93.26487
2014	92.80435
2015	92.69432
2016	92.76814
2017	93.08121
2018	93.41539