Year	% of revenue
1998	9.728794337335263
1999	9.906475869107876
2000	9.763797870318717
2003	11.035377830959222
2005	10.818609529443052
2006	10.642832765603972
2007	9.909498821203133
2008	10.56099345534788
2009	12.848220708648206
2010	12.458297837762917
2011	13.1164527084592
2012	13.662717813605374
2013	13.391778268235505
2014	14.118959909980529
2015	14.518530436579036
2016	16.36204601642594
2017	11.772092005661241
2018	16.532358425894557
2019	15.20698215866795
2020	16.970667036608905
2021	15.576318456036942
2022	16.054216773819384