Year	% net
1971	7.43154
1972	7.88891
1977	9.34184
1978	9.67422
1979	10.08639
1980	10.8048
1981	11.48837
1982	12.50584
1983	13.65414
1984	14.51375
1985	16.02022
1986	17.67218
1987	18.79343
1988	19.29117
1989	19.74278
1991	21.36674
1992	21.8341
1993	22.70059
1994	23.67345
1995	24.94242
1998	28.29705
1999	29.01118
2000	29.99879
2001	31.10795
2002	31.05662
2003	32.99755
2004	35.84748
2005	40.46028
2006	43.7204
2007	49.09273
2008	55.53211
2009	58.93276
2010	57.39892
2011	62.77919
2012	63.99954
2013	65.31431
2014	66.49125
2015	68.14274
2016	74.06397
2017	75.4478
2018	77.69237