Year	% of revenue
2012	15.587270812354056
2013	15.453892592398793
2014	15.601480694975056
2015	20.78421197394155
2016	19.181593457268054
2017	16.087752956980406
2018	16.198905536885057
2019	14.88061854436137
2020	20.08792096451934
2021	19.83217951752597