Year	% of revenue
1990	13.228827030852951
1991	9.368752650390743
1992	8.785583619499985
1993	9.264530417761696
1994	10.219360242919219
1995	10.068829761936216
1996	10.925987890879016
1997	9.868997936404334
1998	8.762935118887
1999	8.844797739733561
2000	9.231836847055584
2001	10.731565333435848
2002	10.098145679685851
2003	8.264634099916671
2004	7.9107240818910505
2005	9.259138381201044
2006	11.860512714075279
2007	12.46128666750598
2008	12.734256289042714
2009	16.913651243032824
2010	13.3956720355159
2011	12.329374388149024
2012	13.618107354134104
2013	11.839272070570257
2014	10.545434531344599
2015	12.633344613981137
2016	13.362849383274867
2017	12.631309594354361
2018	11.896190358772039
2019	13.156571192757566
2020	15.699469333750656
2022	17.36706304689253