Year	% net
1970	58.81266
1971	58.4536
1972	59.80279
1973	63.44395
1974	64.63868
1975	66.55485
1976	67.25174
1977	66.99819
1978	65.03848
1979	65.30091
1980	66.60972
1981	68.0415
1982	68.61436
1983	69.24562
1984	69.93654
1985	71.2494
1986	72.63802
1987	73.11995
1988	74.0077
1989	75.08323
1990	74.77086
1991	75.39339
1992	75.36734
1993	75.80973
1994	76.1548
1995	75.82562
1996	75.77144
1997	76.0539
1998	76.84934
1999	77.99922
2000	78.85754
2001	79.16701
2002	79.64159
2003	82.01725
2004	83.44573
2005	84.22542
2006	84.83086
2007	86.0985
2008	86.58039
2009	86.86459
2010	86.95405
2011	87.159
2012	87.31094
2013	87.33102
2014	87.45087
2015	87.22372
2016	87.37504
2017	87.21036
2018	87.27028