Year	% of revenue
2012	3.4777312210164544
2014	3.9906537333631826
2015	4.834290635364871
2016	5.333173048564752
2017	5.841994118011818
2018	8.90281552362828
2019	6.461241766163401
2020	7.618282382521203
2021	8.304231506299542