Year	% net
1977	44.49664
1978	47.30355
1979	50.78448
1982	58.75061
1983	69.9067
1984	67.10597
1985	72.6233
1986	76.82985
1987	73.83914
1989	75.80844
1992	84.70331
1994	90.47407
1995	91.90458
1997	85.39812
1998	85.41438
1999	84.76823
2000	88.15098
2001	88.95659
2002	86.03916
2003	85.76261
2004	86.78134
2005	87.7959
2006	88.17757
2008	84.73309
2009	85.1202
2010	86.11679
2011	87.53958
2012	84.05848
2013	85.36073
2014	88.29499
2015	91.09603
2016	93.07504
2017	92.35773
2018	90.19346