Year	% of revenue
2012	32.09449071708572
2013	32.67487800436321
2014	34.32863132706339
2015	34.59664252120257
2016	37.47445906482375
2017	35.87900368030804
2018	38.00425931737501
2019	36.717230119441524
2020	36.19831750561488
2021	38.16960953117665