Year	% of revenue
2010	3.7393565657561663
2012	3.3962626313488595
2014	3.773311452348127
2015	4.9037462702397585
2016	6.149528215889506
2017	5.1883524410463
2018	9.007485428885067
2019	6.083435749282201
2020	6.3981864611434