Year	% of revenue
1992	14.642279708973321
1993	13.586238228977365
1994	11.674458928073815
1995	8.715128559982519
1996	11.202601437551815
1997	5.303290803245559
1998	0.8404952739546723
1999	4.4300375518549835
2000	7.356569001226864
2001	7.4426266538481665
2002	6.09899306812115
2003	5.661005540277684
2006	4.727709042263692
2007	5.345201646452441
2008	7.408533476788859
2009	6.100196628899367
2010	6.443769329670565
2011	8.491008170841335
2012	7.094282460525917
2013	7.049630673740072
2014	6.155099214655201
2015	5.90756669841398
2016	6.085054938498273
2017	7.995262073449504
2018	7.100772734142195
2019	6.185704096485939
2020	6.559897020363602
2021	7.013961397438587