Year	% net
1973	34.21934
1979	38.51612
1981	36.49733
1982	36.18197
1983	50.22197
1985	52.72202
1986	51.72821
1987	48.17184
1988	44.23221
1989	44.62412
1990	46.33302
1991	44.54734
1992	42.71635
1993	41.55607
1994	42.6137
1995	44.85301
1998	49.55438
1999	53.23055
2000	56.99608
2001	61.50714
2002	57.0399
2004	70.21871
2005	75.35226
2006	79.21819
2007	84.22039
2008	87.58804
2009	88.58317
2010	89.83316
2011	87.48614
2012	87.73674
2013	88.88743
2014	89.91204
2015	91.51459
2016	90.76644
2017	89.87354
2018	93.92934