Year	% of revenue
1977	6.812941899784813
1978	7.987185947735945
1979	7.41055681531872
1980	9.185938283095869
1981	10.510752688172042
1982	11.603053435114504
1983	13.068085825308328
1984	11.451624073689313
1985	9.51839946796719
1986	9.543953068723342
1987	9.34010152284264
1988	10.654251812788399
1989	10.597151009058265
1990	14.880146262188514
1991	1.549610376424601
1992	3.70320990832774
1993	2.6608125761653096
1994	2.174776757653231
1998	0.5971207329043516
1999	0.6767865130680795
2000	0.5183787059445648
2001	0.4165446680625149
2002	0.40192119585663766
2003	0.009344531196550532
2004	0.007227341954457233
2005	0.005929831078132796
2006	0.0290318567024419
2007	0.0010057702475918986
2008	0.055787618646694896
2009	0.036646756138167466
2010	0.003752728418120387
2011	0.0006265507130147114
2012	0.0006981106440929905
2013	0.02603545937496483
2014	0.7950296038708912
2015	0.5009061941639558
2016	0.4640380439744521
2017	0.036444254245796066
2018	0.0019978878469884293
2020	0.010283478096659084
2021	0.0003053746210925582
2022	-0.0030508517796028244