Year	% net
1986	86.50742
1987	86.70268
1988	85.72971
1989	84.75106
1990	83.75951
1991	83.9591
1992	86.12612
1993	88.35161
1994	89.66471
1995	89.30989
1996	89.25218
1997	88.98883
1998	88.72266
1999	86.50197
2000	85.86423
2001	86.95386
2002	86.44707
2003	88.2761
2004	88.23757
2005	87.92259
2006	87.87472
2007	87.82807
2008	88.2269
2009	87.94749
2010	87.51446
2011	88.87173
2012	88.68028
2013	89.10446
2014	88.92523
2015	90.14432
2016	92.77054
2017	92.54846
2018	92.54153