Year	% of revenue
1998	7.995966725485254
1999	6.759451599501453
2000	5.567471198834379
2001	5.5839042835642205
2002	6.53473137827634
2003	5.875010039177898
2004	5.667414764806172
2005	5.550703573095291
2006	5.0849315701651765
2007	5.189083075017456
2008	4.567615691685862
2009	4.2692571879946515
2010	4.109869247059921
2011	4.2184544015429335
2012	4.261916983010546
2013	4.50003691997261
2014	4.029449354418939
2015	4.041802638225611
2016	4.294756244105814
2017	4.096613470253708
2018	3.752316109621004
2019	3.829224848458758
2020	3.2737524976631587
2021	3.58637909818606