Year	% net
1997	82.57994
1998	82.26287
1999	83.99834
2000	85.38495
2001	87.6171
2002	88.97603
2003	90.45344
2004	89.0023
2005	89.84116
2006	89.98021
2007	90.02103
2008	89.37668
2009	89.03695
2010	89.04917
2011	88.22474
2012	88.82004
2013	89.6237
2014	89.88706
2015	89.33125
2016	89.18509
2017	89.51638