Year	% of revenue
1998	16.703008292018957
1999	19.033075961766436
2000	20.62430810608192
2003	20.612661095047073
2008	13.902897661815564
2009	14.855170045718868
2010	12.5746423933242
2011	10.880098552723389
2012	9.500678581555077
2013	8.341636466222797
2014	8.277321410699415
2015	8.86641733707862
2016	11.273367769579643
2017	11.198264347740434
2018	10.958307635561331
2019	10.875506743385452
2020	11.862420037227272
2021	12.778249103612724
2022	15.269020074454748