Year	% net
1971	17.0148
1972	17.69783
1973	18.06894
1974	20.54241
1977	20.67197
1999	44.04091
2002	51.61313
2003	51.5891
2004	51.60521
2005	56.65099
2006	57.96729
2007	60.112
2009	63.68705
2010	64.28644
2011	64.87843
2012	62.84672
2013	58.63384
2014	59.28886
2015	55.64191
2016	56.98024
2017	61.27746
2018	58.94142