Year	% of revenue
1999	4.524335459744405
2000	3.091564091710509
2001	21.081572075083297
2002	7.153502967312144
2003	7.74927752144449
2004	7.687416546293951
2005	6.537796378166849
2006	3.551998261456498
2007	4.12517127059116
2008	4.846148961390833
2009	12.046253021756648
2010	6.013950986030462
2011	3.6313295363056075
2012	3.7483007943927347
2013	4.295908426175714
2014	5.174118074408255
2015	6.740551844496312
2016	8.063090322502589
2017	7.4454823554734455
2018	4.8451944744037325
2019	5.445180947622508