Year	% of revenue
2008	10.659793581069149
2009	9.84525204410525
2010	9.049425772521332
2011	8.447229020006839
2012	9.94914710046491
2013	10.476902542124364
2014	10.839176428181522
2015	12.55968379341876
2016	12.72238776248719
2017	13.00461453311864
2018	12.373991351863403
2019	11.282113449880045
2020	12.342963594949788