Year	% net
1975	73.02254
1976	73.80958
1977	74.84289
1978	75.28913
1979	75.66325
1980	76.22538
1981	76.17909
1982	76.51036
1983	76.9873
1984	77.35963
1985	77.9843
1986	79.18123
1987	79.79006
1988	79.97229
1989	80.26761
1990	80.39367
1991	81.48579
1992	83.03105
1993	85.74047
1994	88.4436
1995	88.64476
1996	88.9461
1997	88.64937
1998	86.58209
1999	86.19609
2000	86.81765
2001	87.22753
2002	88.03141
2003	88.46882
2004	89.46641
2005	90.67789
2006	91.22277
2007	90.72391
2008	91.25926
2009	91.16182
2010	91.3596
2011	90.81806
2012	90.61763
2013	90.02466
2014	89.83049
2015	90.03888
2016	90.38816
2017	90.58376
2018	90.60507