Year	% of revenue
2011	30.897531693569192
2012	21.380381924191216
2014	24.932040138268956
2015	28.247306400900232
2016	27.056042502878363
2017	27.510259862476893
2018	28.783728765164636
2019	24.796621472933584
2020	25.29115662021254
2021	31.474298929774065