Year	% of revenue
1972	1.1836115326251897
1973	1.1708482676224612
1974	1.3296832225263981
1975	1.2024048096192386
1976	1.199580146948568
1977	1.1317278589288065
1978	1.3398838767306833
1979	1.2263099219620959
1980	1.111265453535213
1981	1.1537981788699014
1982	1.2500651075576854
1983	1.2457479084306335
1984	1.1822920601344715
1985	1.1680903081705956
1986	1.511861893666596
1987	1.9728901680438213
1988	1.7724710768318008
1989	1.847457159413891
1990	1.7469636418073653
1991	1.7030384812246988
1992	1.8880670111797886
1993	1.771029800075443
1994	1.7362355953905249
1995	2.034985168382481
1996	2.0566564806897714
1997	2.174075934472452
1998	2.0559218729737547
1999	1.9086994986202792
2000	2.0664439571249975
2001	1.86643512670052
2002	2.098574285529966
2003	2.369545650736036
2004	2.1244480772654217
2005	2.035008999416939
2006	2.0077068232085065
2007	1.984961045080976
2008	2.041972619390788
2009	2.173127386606841
2010	2.077391719844331
2011	1.9914205578158157
2012	2.2002204627576356
2013	2.0785777873490607
2014	2.0211466250348176
2015	1.8473252316972393
2016	1.9564629245974834
2017	1.7920130017622442
2018	1.901648591173696
2019	1.9984995502821912
2020	1.8472255533930848
2021	1.7493447958039074
2022	1.7587352117758204