Year	% of revenue
1998	40.54692462826024
1999	35.077927888451725
2009	24.739593726304026
2010	24.97118801807319
2011	18.244447753145838
2012	42.363125391891955
2013	45.227984786441866
2014	47.18326218042192
2015	54.32698835592057
2016	59.790511313460534