Year	% of revenue
1975	1.7003493037949948
1976	1.526687929914305
1977	1.9885550786838426
1978	2.3701462430660625
1979	2.1653752255599192
1980	1.634108476988257
1981	2.003572260619713
1982	2.0922459893048106
1983	2.463682151182151
1984	4.440949950697545
1985	4.62683341442625
1986	3.4517980371516304
1987	3.1570422417649064
1988	2.5122284188010746
1989	1.9749005901273966
1990	1.8361826002532449
1991	1.7112869545781737
1992	1.9691689373201995
1993	2.271438501439888
1994	1.7675324704915747
1995	1.2943571844095403
1996	1.9490320044825458
1997	1.584290389146385
1998	0.8788786172601658
1999	0.991707431836341
2000	0.9202108891850471
2001	0.918264154372733
2002	0.9840268874952358
2003	1.4865526349037725
2004	1.353394849478848
2005	1.174229979307594
2006	1.3350371964966663
2007	1.5039532096274066
2008	1.5447067516719892
2009	1.228817355989838
2010	1.262450770492336
2011	1.2467191069239314
2012	1.0866549939040053
2013	1.0379502643655647
2014	1.2336929179692784
2015	1.3957045855937469
2016	1.379999566668111
2017	1.3118578890654489
2018	1.205135310336699
2019	1.6544357679088708
2020	0.9856808115911377
2021	1.5392704291407722
2022	1.6738171202288143