Year	% of revenue
1972	3.7365716954694066
1973	2.817974105102818
1974	1.537968599807754
1975	1.7162471395881007
1976	1.5197568389057752
1977	1.1650485436893203
1978	1.1685552407932012
1979	0.9526601201817383
1980	0.7495870918561809
1981	0.8105057966553811
1982	0.7140307033202428
1983	0.7172743574417215
1984	1.1909110835099
1985	1.7642531525664555
1986	2.1612996808819265
1987	2.1029267925663984
1988	3.087128933031909
2001	0.004212497074654809
2002	0.0029060490927969866
2003	0.0027236412786073726
2004	0.0043971759161077996
2005	0.003944340787922534
2006	0.004704480233342219
2007	0.003036790719567561
2008	0.5452959139159518
2009	0.002152268519909495
2010	0.0024528399874693186
2011	0.0023650588692197133
2012	0.000207542079156549
2013	5.27389999630827E-05
2014	0.0003647097306694096
2015	0.00026240132517440145
2016	5.666532067353012E-05
2017	0.0010020742937799586
2018	0.003039709586763694
2019	0.004357233275449736
2020	0.004625280461493822
2021	0.004898963747654515
2022	0.0057207572689924055