Year	% of revenue
2002	20.421692389347378
2003	19.119467657072114
2004	19.470399781510224
2005	20.76830912328738
2006	19.5528946691575
2007	19.797332514621225
2008	20.49340061810691
2009	20.944539145517165
2010	21.645807920509384
2011	23.67846972436859
2012	22.426137891423366
2013	22.85736180265853
2014	23.289037824512747
2015	25.461882481686615
2016	24.605815541293087
2017	23.872198725992906
2018	25.31968397474881
2019	24.19226767246363
2020	25.12650412501208
2021	25.438594574727134