Year	% of revenue
2001	4.47974419173237
2002	3.522907083963066
2003	3.2639547401982805
2004	3.933471055664502
2005	3.959351693002447
2006	3.315796879838255
2007	3.519401864238225
2008	4.414047998848579
2009	3.440537361203428
2010	3.106353071291035
2011	3.086613977719711
2012	2.8231682307433417
2013	2.7642485853345637
2014	2.821785988386191
2015	3.085108773203595
2016	2.838827838827839
2017	2.476253425396471
2018	2.448543349587109
2019	2.133768326115891
2020	1.5559523818566154
2021	1.2778692954351925