Year	% of revenue
2011	9.708873982198568
2012	22.192957012349297
2014	24.282947368421056
2015	26.8786148843145
2016	27.44253140481415
2017	28.83842302157509
2018	28.17436596761818
2019	28.39044401855299
2020	27.88897568598432
2021	27.65601148075228