Year	% of revenue
2008	39.68898419999684
2009	39.84097120117576
2010	41.120158794661
2011	39.51428507820544
2012	41.38576356790151
2013	40.808990915714276
2014	39.200495285027976
2015	39.82335565542065
2016	40.07058705684269
2017	39.94493463062247
2018	41.928235388065964
2019	40.61649243367323
2020	39.96859718170147
2021	39.98962780228338
2022	39.81886147576624