Year	% net
1978	11.79169
1979	12.12116
1980	12.59735
1983	14.02579
1984	14.38097
1985	14.52848
1986	14.69314
1987	15.00227
1988	15.29789
1989	15.3706
1990	15.18779
1991	15.92764
1992	16.5702
1993	17.13433
1994	17.80253
1995	18.94715
1996	19.75484
1997	20.59943
1998	21.84085
1999	22.85927
2000	24.09167
2001	24.99658
2002	25.90688
2003	27.0216
2004	27.04373
2005	27.8201
2006	28.77601
2007	29.77278
2008	30.60892
2009	31.93847
2010	33.32735
2011	34.20627
2012	35.36892
2013	35.57375
2014	36.4531
2015	37.81075
2016	38.34429
2017	38.66645
2018	37.76916