Year	% of revenue
1972	3.4482758620689653
1973	2.941176470588235
1974	2.1052631578947367
1975	2.2388059701492535
1976	2.3529411764705883
1977	2.4896265560165975
1978	2.1739130434782608
1979	2.050113895216401
1980	2.9717682020802374
1981	1.8306636155606408
1982	1.593625498007968
1983	1.4198782961460445
1984	1.3775290572535515
1985	1.0016465422612513
1986	1.7655125128556735
1987	1.5350947768158851
1988	1.8356772760917839
1989	1.7673336864162847
1990	1.905098212315162
1991	2.457026799425373
1992	2.3825304155884575
1993	2.759987393903136
1994	1.8977414568663007
1995	1.832019241716953
1996	2.0579236564958583
1997	1.9726193759715034
1998	1.570998305453486
1999	1.4553896573967324
2000	0.7251239791764328
2008	0.606421370704185
2009	1.091296855333113
2010	1.0009118076810029
2011	0.9659845979962948
2012	1.0098509941839537
2013	1.0064135441892192
2014	0.8170185868989667
2015	1.014798921861309
2016	0.9502373826368699
2017	0.9893818688237083
2018	1.0435672689394075
2019	0.884290617022776
2020	1.2692500411009948
2021	1.1134683204751532
2022	1.4745866521234805