Year	% net
1981	83.9163
1982	83.51671
1983	83.05297
1984	82.88703
1985	82.45169
1986	81.75617
1987	81.13319
1988	80.76703
1989	80.0272
1990	80.33889
1991	80.78942
1992	81.63241
1993	82.768
1994	83.59376
1999	87.27123
2000	86.8454
2001	85.92521
2002	85.38522
2003	85.54975
2004	86.38399
2005	86.99467
2006	87.41503
2007	86.84854
2008	86.36575
2009	85.33584
2010	84.93788
2011	84.30245
2012	82.21341
2013	84.47916
2014	85.43395
2015	86.16997
2016	86.89822
2017	86.66088