Year	% net
1975	30.47711
1976	33.41204
1977	35.63422
1978	38.23697
1979	40.36682
1980	42.68273
1981	45.23527
1982	46.07397
1983	48.46205
1984	50.58358
1985	49.72355
1986	48.40702
1987	46.99889
1988	45.92193
1989	44.54752
1990	45.7915
1991	45.73745
1992	46.64296
1993	48.87817
1994	51.81853
1995	54.90639
1996	57.56251
1997	59.51682
1998	60.48058
1999	66.43787
2000	72.11288
2001	77.04938
2002	81.80179
2003	83.52307
2004	83.60875
2005	84.64945
2006	85.97781
2007	87.54116
2008	88.37824
2009	88.64363
2010	91.65842
2011	92.88851
2012	92.25834
2013	93.01111
2014	93.17198
2016	94.65637
2017	96.96158