Year	% of revenue
1998	27.588322959425827
2003	23.996109631053564
2008	28.734486989822965
2009	26.938131509905073
2010	27.293172041814127
2011	26.147332391230837
2012	24.43426338445236
2013	21.972377122146916
2014	24.885420794046865
2015	25.95165308379927
2016	24.255825254109034
2017	24.43139413966033
2018	23.991542188757897
2019	24.86684099661258
2020	23.4321426324322
2021	25.226065342010045
2022	27.024695076206346