Year	% of revenue
1990	15.41995549718002
1991	16.23306693872924
1992	18.47114425703508
1993	16.6811777102798
1998	13.654076995031836
1999	12.831229669784648
2001	14.81988948251183
2002	13.638532318527774
2003	11.151927525640666
2004	11.174050294892602
2005	14.225009678114388
2006	14.090728168775101
2007	9.454657614708156
2008	8.262539225245927
2009	6.960821021402309
2010	7.917912899665108
2011	7.373045536653702
2012	6.704845623230421
2013	6.16301341519427
2014	5.994306410348497
2015	5.45160843956745
2016	6.699554673162253
2017	5.8664526981518055
2018	5.181736391670295
2019	4.820590397144599
2020	4.925135369157005
2021	5.561064213886793