Year	% of revenue
1998	12.48143010230497
1999	13.391152874913189
2000	15.218790229932413
2003	12.926805337519625
2004	11.621731870893855
2005	12.400288431590486
2006	13.943077580247923
2007	16.127267056622017
2008	19.6422065849023
2009	16.967441362321946
2010	16.572963286821313
2011	16.336549510270615
2012	16.68929490634504
2013	15.382350632016959
2014	15.249102630512667
2015	15.761828952572326
2016	15.284102386929034
2017	16.536558157956303
2018	16.78979988972189
2019	16.112305552443274
2020	15.999259842210483
2021	14.826156514413695
2022	15.23384404497522