Year	% net
1976	74.64697
1977	75.66873
1978	76.30042
1979	76.8138
1980	77.53734
1981	78.03922
1982	78.54658
1983	78.96986
1984	79.24453
1985	79.92749
1986	81.11671
1987	81.65428
1988	81.85219
1989	82.18008
1990	82.35201
1991	82.56359
1992	83.25554
1993	86.14237
1994	87.87781
1995	88.03646
1996	88.53078
1997	88.36377
1998	87.24938
1999	87.45912
2000	87.94779
2001	88.8138
2002	89.56276
2003	90.0409
2004	90.55896
2005	91.57889
2006	91.47178
2007	91.07579
2008	91.66863
2009	91.80064
2010	92.09045
2011	91.20971
2012	90.71215
2013	90.97327
2014	91.28471
2015	91.66879
2016	91.771
2017	91.79638
2018	91.82051