Year	% of revenue
1990	26.019749233170103
1991	23.43381140491358
1992	23.00903774587985
1993	19.419810611754095
1994	19.103089733293885
1995	16.78708442099608
1996	16.536783042394017
1997	15.538499081971786
1998	15.455219169434303
1999	13.678351492183799
2000	11.077272874314312
2001	10.912474080996624
2002	11.911699713106465
2003	13.956638612885975
2004	15.202454639474826
2005	13.669183399748247
2006	14.560810277615568
2007	14.185548575327639
2008	14.309791531011054
2009	18.917644983364713
2010	15.673804991423543
2011	16.641453937554544
2012	20.312365238586295
2013	16.63169486087869
2014	16.721170056090912
2015	16.719059454216957
2016	21.51421326626933
2017	20.18611769357349
2018	17.68265487853857
2019	17.557408497871194
2020	26.333721135919987
2021	24.102715255338445
2022	17.104529705393897