Year	% of revenue
2003	10.583498860092398
2005	9.745177263277348
2006	9.30218905733432
2007	8.810168904112249
2008	9.902776837878685
2009	12.447788368855091
2010	12.05001534839269
2011	13.1164527084592
2012	12.413670820251358
2013	12.982348294810139
2014	12.180952894035126
2015	12.10662461195238
2016	12.08834060977058
2017	10.666079646912692
2018	11.493001063602282
2019	13.71102779627314
2020	15.567846444845232
2021	14.037768905191363