Year	% of revenue
2012	17.31427111002441
2013	18.107510951629916
2014	16.330633244271276
2015	17.53556308635681
2016	16.78384509025455
2017	16.3004428065299
2018	15.229819454158022
2019	15.649571953428826
2020	13.744172380837155
2021	14.76011049496183