Year	% of revenue
1972	1.7023346303501945
1973	1.4474772539288667
1974	1.3669064748201438
1975	1.5893610120012975
1976	1.408811475409836
1977	1.2790941497169217
1978	1.271431323444423
1979	1.2824572514249524
1980	1.0959636460839348
1981	1.1063140852671345
2003	0.07878424181062958
2004	0.8821594022437382
2005	1.1790641551075798
2006	0.29685055087992684
2007	0.2916306716803393
2008	0.4286505667435356
2009	0.2727342423387288
2010	1.1277610939191145
2011	0.42161381915081664
2012	0.28801857713574835
2013	0.2812858145134677
2014	0.3922667897350654
2015	0.31252539978867006
2020	0.46520828963132244