Year	% of revenue
1990	17.1580042821438
1991	27.585598305683025
1992	12.881451508219099
1993	30.413735630775264
1994	34.84439105667682
1995	35.77566726815091
1996	11.680726800778714
1997	13.021052631578947
1998	12.018822299196131
1999	12.795489047928864
2001	13.051507272020688
2002	12.371995602711392
2003	8.838799188878351
2004	8.513755810728082
2005	9.355509649374449
2006	9.121307138307776
2007	7.476908188327415
2008	9.911799212497915
2009	8.038127484914206
2010	7.7471842257740615
2011	7.081206121240283
2012	8.397496444673868
2013	6.693664962033857
2014	5.9489734597004285
2015	5.270224601428478
2016	4.38823529198256
2017	5.442567701167636
2018	5.629926421421071
2019	5.87026072274371
2020	4.972427709451379
2021	4.916570917320994