Year	% of revenue
1996	18.95820560258354
1997	19.265667526728603
1998	19.619593901828306
1999	19.957720891824938
2000	18.82291277134432
2002	20.118459490606323
2003	21.125287249696672
2004	19.198679337884265
2005	18.22332646621964
2006	20.103910129978804
2007	16.45893595432448
2008	20.43096601006868
2009	21.789496110783325
2010	24.20944606644116
2011	20.491290700671524
2012	22.02653430663783
2013	24.52663656567995
2014	24.210529070998362
2015	21.917157776821313
2016	23.160346452604102
2017	22.93366552079652
2018	23.205195297399793
2019	24.008750617803045
2020	26.917309184413018
2021	24.299623690568474
2022	23.54179310972984