Year	% of revenue
1972	2.5405921680993386
1973	2.769026695407074
1974	1.9797120418848118
1975	1.346902125112247
1976	1.7026683608640374
1977	2.07083958020989
1978	1.9592268996558213
1979	1.9622199443549573
1980	1.9869838161608022
1981	2.2487944099990176
1982	1.9667710852928448
1983	1.9226771980877182
1984	3.5283517888801796
1985	3.660288308623605
1986	7.844746716697933
1987	6.745695738075076
1988	8.98350007466029
1989	9.253811602454592
1990	9.251957415648063
1991	9.985228543423943
1992	9.74209412706584
1993	10.079583623324408
1994	9.541457615859288
1995	1.845393139375745
1996	1.5610258169654345
1997	1.4988309953239813
1998	2.3274058577405854
1999	2.02952679609598
2000	2.4656791907514455
2001	2.2233054404636174
2002	2.4284475281873372
2003	4.463687795866528
2004	6.652096418265149
2005	6.781583547175425
2006	5.594167926997128
2007	7.342497136311568
2008	5.912275650254344
2009	4.55212043216712
2010	4.85384440400364
2011	4.403690496405728
2012	4.269964501140004
2013	4.879765037018907
2014	4.641930950552714
2015	5.2154586782881776
2016	4.687110706596441
2017	4.624398658110751
2018	4.124800495222096
2019	3.9489498343353504
2020	3.735272350367569
2021	3.584009196388502
2022	4.179851891401498