Year	% of revenue
1972	2.8224582701062215
1973	2.986857825567503
1974	2.6202581149784905
1975	2.1209084836339342
1976	1.949317738791423
1977	1.9739439399921042
1978	1.9205002233139794
1979	2.0438498699368264
1980	1.8613696346714823
1981	1.8148933516277908
1982	1.776134173654878
1983	1.9490668382826148
1984	1.8093223540077057
1985	1.6781865926171864
1986	1.562169031984749
1987	1.562064803639402
1988	1.1699050726787303
1989	1.1493142746764535
1990	1.0440125489787682
1991	0.9701735610255455
1992	1.3510318505758774
1993	1.3249717087891362
1994	1.3555271020059754
1995	1.3617460594427966
1996	0.9268566209606732
1997	1.00800084365469
1998	0.8755374225662613
1999	0.8656581909512282
2000	1.3501116963498863
2001	1.7742698840283684
2002	1.8734275208051092
2003	1.6745354936884886
2004	1.5073978331782976
2005	1.3695591553223312
2006	1.3252416500395083
2007	1.2202181725126353
2008	1.243075682207716
2009	1.2339572502120377
2010	1.2157078384132736
2011	1.3009017386030042
2012	1.316648132549361
2013	1.2889847993091785
2014	1.309630540218557
2015	1.3196980781859764
2016	1.243241057592364
2017	1.292383600215631
2018	1.3194694336538744
2019	1.2975439422670245
2020	0.9800480364151551
2021	1.2341950830958275
2022	1.2539910858343335