Year	% of revenue
1972	0.7179781734635268
1973	1.1398963730569949
1974	1.3023442195952715
1975	0.8914218909834867
1976	1.539708265802269
1977	1.251303441084463
1978	1.8256772673733805
1979	7.869927585735756
1980	6.850618458610846
1981	7.560207296006503
1982	8.47788907891522
1983	9.855013687519012
1984	6.265346534653466
1985	3.079341055940392
1986	0.9314105968381061
1987	0.7465119311513887
1988	0.502596400492169
1989	5.589222298243899
1990	3.8446809092649836
1991	6.715264375806024
1992	3.5086674856985134
1993	7.786614752736165
1994	5.78607622530374
1995	5.775638086504661
1996	3.78360140274303
1997	3.047323430148055
1998	3.1895509467370005
1999	3.877405528436851
2000	4.492285651110051
2001	4.834871768038341
2002	6.567788291800499
2003	9.349673998194218
2004	11.665249332792241
2005	7.627866514284473
2006	8.374100365480789
2007	6.830265281066426
2008	9.687932880147534
2009	12.88441482709361
2010	12.510860956538306
2011	14.097381206903387
2012	16.169227711594935
2013	14.863287982323548
2014	15.806004651672541
2015	14.149943061529902
2016	17.919732958264785
2017	18.861314136383818
2018	16.99788268299588
2019	17.74471318910015
2020	21.60040734709441
2021	18.957634514667923
2022	17.780032604721615