Year	% net
1970	58.40523
1971	58.0678
1972	59.45614
1973	63.15677
1974	64.39921
1975	66.36527
1976	67.0907
1977	66.85058
1978	64.89149
1979	65.15228
1980	66.46181
1981	67.87441
1982	68.4415
1983	69.06994
1984	69.75828
1985	71.05681
1986	72.44726
1987	72.92869
1988	73.821
1989	74.91382
1990	74.60664
1991	75.24097
1992	75.23216
1993	75.67368
1994	76.03315
1995	75.7173
1996	75.67056
1997	76.02206
1998	76.7393
1999	77.903
2000	78.77275
2001	79.08673
2002	79.57133
2003	81.96642
2004	83.39368
2005	84.17897
2006	84.78514
2007	86.05636
2008	86.54374
2009	86.83727
2010	86.92192
2011	87.1294
2012	87.28122
2013	87.3024
2014	87.42231
2015	87.19269
2016	87.35857
2017	87.19902
2018	87.26031