Year	% of revenue
1998	1.7691416220432585
1999	2.1829217123013067
2000	1.363609151854843
2003	1.304272543505844
2005	2.0361443867125066
2006	2.4427558691367137
2007	1.2123562489745388
2008	0.978551412316941
2009	1.6846246815554766
2010	1.5612300337589957
2011	1.5206494604011578
2012	1.9380826580378798
2013	1.1605032777566877
2014	1.4594427503498228
2015	2.6026081397997993
2016	2.356919459954155
2017	2.039737200376401
2018	1.2662455636228565
2019	1.612790244410794
2020	1.4473920386265173
2021	1.364542792173987