Year	% of revenue
2008	14.631016836015723
2009	15.155406625599454
2010	15.8521347883625
2011	15.349502653138995
2012	13.623496245963594
2013	13.486793286103904
2014	16.251257003304122
2015	15.459157403729968
2016	16.029346026620903
2017	15.802730888416894
2018	15.782030020120047
2019	15.442197110449035
2020	16.721024077832443
2021	18.337529873629766
2022	16.650407618198418