Year	% of revenue
2010	35.9805640796043
2011	29.725166146519605
2012	27.7705180021236
2013	28.827486964686862
2014	23.594155879696398
2015	23.002836707657643
2016	20.074346908626207
2017	22.815816186324543
2018	21.184292032836403
2019	20.95375912301175
2020	19.549544120385594
2021	19.52670255248384