Year	% of revenue
1973	11.806142575373345
1974	4.3705153294194385
1975	8.599916909015372
1976	10.56411225550411
1977	8.54926696215479
1978	10.096426545660805
1979	11.093088857545839
1980	11.6511281513764
1981	13.116256632899178
1982	14.650238126447329
1983	13.719052564575026
1984	10.360838821280083
1985	15.921668795232014
1986	15.2225253938046
1987	15.804315158711018
1988	13.460156858049452
1989	8.961951650407244
1990	9.396524907790074
1991	6.270451932431237
1992	10.270801178616528
1993	10.398514612738321
1994	12.121468091396714
1995	16.49133578933006
1996	13.204348802853815
1997	17.433148665154423
1998	16.49223579808207
1999	13.954307346920809
2000	12.456432192648922
2001	14.882542264840112
2002	16.954982906923494
2003	16.617646617916453
2004	15.764516224689784
2005	11.203887482034089
2006	11.411072797114132
2007	11.61294370393127
2008	12.61905417308963
2009	16.946785407457952
2010	13.5913093329247
2011	13.17197653170212
2012	12.87719818932605
2013	11.806359710669248
2014	12.069506373545575
2015	15.442502119399101
2016	12.88969199992531
2017	14.950126458277877
2018	13.785410611013596
2019	10.047173989100305
2020	13.09488905395261
2021	9.770591190169212
2022	14.569304263267574