Year	% net
1974	24.23338
1986	38.65903
1987	39.98554
1988	41.61897
1989	43.23052
1990	44.26098
1991	46.12145
1992	47.58777
1993	50.81063
1997	54.59374
1999	57.91036
2000	64.45987
2001	72.65051
2002	72.07506
2003	72.13827
2004	74.05944
2005	76.35578
2006	78.89809
2007	80.55242
2008	79.85273
2009	76.51685
2010	80.94061
2011	84.20113
2012	81.2314
2013	86.87212
2014	87.44485
2015	86.64416
2016	85.28003
2017	87.22819