Year	% of revenue
2008	4.910323709536308
2009	5.382566570504672
2010	4.461086693355827
2011	4.690366130261513
2012	4.875080877968444
2013	5.35193723233151
2014	5.006287421884338
2015	6.2865965016521415
2016	7.60957742867575
2017	7.73970302969854
2018	9.415049653900795
2019	8.298468896399513
2020	9.128856642134263
2021	8.678013351401084