Year	% of revenue
2010	23.149453960951288
2011	23.039125794831676
2012	22.19124237979616
2013	21.942753140369334
2014	21.427787762389116
2015	20.228163123855918
2016	18.89320460381373
2017	20.772810069384864
2018	20.924164822325807
2019	19.0565095577259
2020	18.94165287527371
2021	19.706900213532258
2022	16.202538303653093