Year	% of revenue
1990	18.9162466072121
1991	11.64741132292716
1992	15.950810126914774
1993	17.743105463240333
1994	19.989278752436647
1995	7.302097885678731
1996	7.01371911518848
1997	9.836239819966428
1998	13.164584743127824
1999	6.759451599501453
2000	6.911790175862871
2001	7.897830501229026
2002	6.364888723711896
2003	5.1366494945974575
2004	4.686220228889364
2005	5.151741150823246
2006	4.583824569676962
2007	4.464152264564732
2008	4.375443723949882
2009	3.6014243113924427
2010	3.91595611979254
2011	4.037137366204615
2012	4.151835164957731
2013	4.037776187612784
2014	3.6728889110191405
2015	3.760003051331346
2016	3.838541074877855
2017	3.4804795194691347
2018	2.840164063468072
2019	2.595598878648515
2020	2.82505249354924
2021	3.156601545584439
2022	3.242856767601148