Year	% of revenue
2011	6.705131614285537
2012	7.869147051522869
2013	10.933774573152686
2014	10.319222428423245
2015	15.254093980929643
2016	15.221357710641708
2017	4.869661003876461
2018	3.5555957147431734
2019	2.702074791965101
2020	3.1136815423487496