Year	% of revenue
1974	0.06350550381033022
1975	0.09003678645846731
1976	0.12725344644750797
1977	0.14373323112303565
1978	0.14375306067642923
1979	0.14841044601244566
1980	0.15688703101615317
1981	0.1590934227205826
1982	0.16871495443042162
1983	0.15325251087819164
1984	0.15817457645422148
1985	0.16063775586657475
1986	0.16029426652718254
1987	0.14911097486204783
1988	0.1294400261212305
1989	0.12181962656409907
1990	0.10726351556780345
1991	0.7090516974767739
1992	1.022060432456088
1993	1.1302837492253848
1994	1.3814825906672448
1995	1.2616008540067318
1996	1.369026419367506
1997	1.493738870534615
1998	1.184200796509724
1999	2.1445714693383624
2000	3.4321232435612035
2001	3.0057975776758097
2002	3.2219390794328597
2003	3.9694325033356423
2004	4.862112925953395
2005	4.893408207060889
2006	4.694880303514857
2007	4.809545876021714
2008	4.642388451443569
2009	4.904771069876743
2010	6.4411818102613125
2011	4.384576900715685
2012	4.406914673819391
2013	3.870774681598805
2014	4.910187055675679
2015	5.125771253168787
2016	5.034871613331959
2017	5.178920023102279
2018	5.072438795200369
2019	5.288419733342177
2020	4.996854826551331
2021	3.5876191099775663
2022	3.7796980419254713