Year	% net
1986	90.43082
1987	93.13976
1988	94.40235
1989	95.47263
1990	94.39005
1991	95.01155
1992	94.90887
1993	94.16073
1994	93.19216
1995	91.83783
1996	90.96404
1997	90.26731
1998	92.21298
1999	94.25191
2000	94.35187
2001	94.46134
2002	94.40528
2003	94.36236
2004	94.4962
2005	94.33375
2006	93.88656
2007	95.02517
2008	95.08888
2009	95.39318
2010	95.51326
2011	95.70736
2012	95.71035
2013	95.49649
2014	95.69194
2015	95.90841