Year	% net
1997	81.55924
1998	81.59047
1999	83.50017
2000	85.0428
2001	87.41386
2002	88.99301
2003	90.55161
2004	89.71743
2005	90.00626
2006	90.084
2007	90.00401
2008	89.64615
2009	89.1824
2010	89.09243
2011	88.39353
2012	88.94628
2013	89.67352
2014	89.78721
2015	89.1319
2016	89.15815
2017	89.27911