Year	% net
1986	85.7083
1987	88.47438
1988	89.52403
1989	90.87074
1990	91.97665
1991	92.59596
1992	92.33943
1993	91.88433
1994	90.89825
1995	89.97503
1996	89.42518
1997	89.17746
1998	91.18051
1999	93.45501
2000	93.76546
2001	94.1993
2002	94.63453
2003	94.90108
2004	95.27114
2005	95.35887
2006	94.70748
2007	95.28597
2008	95.52129
2009	95.51561
2010	95.31375
2011	95.18209
2012	95.06046
2013	94.99398
2014	95.04166
2015	95.08825
2016	95.18889
2017	94.95664
2018	95.08598