Year	% net
1971	24.58102
1972	26.8205
1999	48.53344
2000	51.45313
2001	54.80014
2002	57.32278
2003	58.95968
2004	61.33545
2005	63.14279
2006	66.58989
2007	68.83938
2008	69.97967
2009	71.68989
2010	71.94629
2011	73.03338
2012	74.79369
2013	75.07477
2014	75.72595
2015	74.55316
2016	73.3043
2017	73.24477