Year	% of revenue
1972	3.9345203905801265
1973	3.9378238341968914
1974	3.386094970947706
1975	2.8204004091772616
1976	3.3387358184764993
1977	3.2772232980783556
1978	3.680800942285041
1979	4.057931411395
1980	3.8481869119357226
1981	3.648003251702063
1982	4.764231614952358
1983	4.390144986312481
1984	4.689108910891089
1985	3.4577099947610455
1986	3.096531721067037
1987	3.8662146303298996
1988	3.6599862359491984
1989	4.0286058710455155
1990	5.180950296796783
1991	5.325016234805594
1992	4.053125219866754
1993	4.302366990337362
1994	4.508833041938598
1995	4.3668806357939784
1996	4.6716224510673126
1997	4.740828331102517
1998	4.723998146009137
1999	4.688859190334065
2000	4.877500561924028
2001	4.397436689588419
2002	4.238346091973666
2003	3.0030736426734483
2004	0.6540086250796616
2005	0.7412614001941127
2006	1.329068826292275
2007	1.227101035991309
2008	1.7573662575142004
2009	2.575415103690274
2010	3.0398709643452233
2011	1.6843802974584456
2012	1.5800601283967608
2013	1.4988501522915063
2014	1.954635640496868
2015	2.0329176424710065
2016	1.8615281883214367
2017	1.5518688185868978
2018	1.4984003776197325
2019	1.3832488894210655
2020	0.7384909702960337
2021	0.5712737786423071
2022	0.7628376905051288