Year	% of revenue
1974	2.7237354085603114
1975	9.967585089141005
1976	8.095838587641866
1977	9.63760798833165
1978	5.259062317618832
1979	3.2721942716792776
1980	2.3806205223984613
1981	1.2698412698412698
1982	1.7920173771382024
1983	4.5287152713033745
1984	4.840932899597508
1985	6.817267730258749
1986	6.016427329301237
1987	8.170328805915359
1988	10.499867157551144
1989	8.11659614480489
1990	9.428449820553105
1991	9.77647265404632
1992	6.209232204722369
1993	5.503148058596954
1994	4.390064175286166
1995	3.3558498834628963
1996	2.5077261358742056
1997	1.9194533143905825
1998	3.0259468814829904
1999	1.5614550468850452
2000	5.6459100131117435
2001	5.512219445048943
2002	5.549161098373352
2003	5.545290697015382
2004	4.371628134962661
2005	3.5308312694481487
2006	2.6868052440057824
2007	2.215127507391198
2008	1.921526841798748
2009	2.780416039747198
2010	2.0968698714471303
2011	2.422506770417882
2012	2.7429906520738188
2013	2.799566499046298
2014	2.637856704329355
2015	3.1154184358207844
2016	3.641432383621221
2017	3.718071393728823
2018	4.120618743137394
2019	4.1205347224462265
2020	4.542446636746445
2021	3.5437231843498154
2022	3.8183944882078817