Year	% of revenue
2006	4.219004887647582
2007	3.6324346868018678
2008	1.9006927102162432
2009	3.5202727968717027
2010	2.9989662646718296
2011	2.697366562140031
2012	3.723815706719159
2013	3.6170219555677634
2014	4.8760524543205745
2015	5.998665107872634
2016	3.9694848231868343
2017	4.530615622952129