Year	% net
1981	73.95649
1982	73.89013
1983	73.70502
1984	73.56879
1985	73.67363
1986	73.41359
1987	73.19692
1988	73.37438
1989	73.45012
1990	74.17736
1991	75.36394
1992	76.03702
1993	77.117
1994	78.43564
1999	81.8454
2000	82.34832
2001	82.25319
2002	81.24886
2003	81.05452
2004	81.46374
2005	82.34026
2006	82.9207
2007	82.76726
2008	82.60969
2009	81.85771
2010	82.3699
2011	82.04877
2012	80.06983
2013	82.58785
2014	83.47382
2015	84.0442
2016	84.70193
2017	83.93147