Year	% net
1971	4.50091
1973	6.61697
1977	9.66879
1978	9.54373
1979	11.40432
1980	11.89129
1981	12.29596
1982	12.82625
1983	11.39326
1984	11.53595
1985	11.86896
1986	12.18406
1991	13.60304
1992	15.27388
1993	15.98705
1994	14.91292
1996	16.46014
1998	12.3668
1999	16.21034
2000	17.97381
2001	20.04806
2002	20.91766
2003	21.89832
2004	23.20564
2005	25.0859
2006	25.8478
2007	27.23189
2008	29.59115
2009	32.39088
2010	36.12128
2011	38.96832
2012	40.16248
2013	40.63024
2014	40.64296
2015	41.85947
2016	41.35206