Year	% of revenue
2010	9.370275544792555
2012	9.49948207854234
2013	9.482776175123027
2014	9.158519669229435
2015	10.573941849492368
2016	9.476047925537918
2017	9.507397667379337
2018	10.204735964997292
2019	9.865071254656606
2020	9.441511638715411