Year	% net
1976	12.12234
1977	11.89268
1978	12.28831
1979	12.84325
1980	13.71578
1981	13.68296
1982	14.41278
1983	15.12198
1984	15.43429
1985	15.31957
1986	15.2602
1987	15.44231
1988	15.57661
1989	15.62565
1990	15.29696
1991	16.21611
1992	16.96293
1993	17.64156
1994	18.55191
1995	19.71152
1996	20.48693
1997	21.11619
1998	22.19568
1999	23.03513
2000	24.04056
2001	24.88436
2002	25.84814
2003	26.28803
2004	26.58309
2005	27.0964
2006	28.23262
2007	29.15138
2008	30.01052
2009	31.34445
2010	32.48536
2011	33.08418
2012	34.27019
2013	35.18394
2014	36.12135
2015	37.28353
2016	37.99336
2017	37.93698
2018	38.05158