Year	% of revenue
1992	15.701909451530696
1993	14.185024702916847
1996	14.829715261926438
1997	14.575679458919232
1998	17.169730471345666
1999	19.795525319635672
2001	19.393477106677846
2002	18.970688168847808
2003	25.49041508142831
2004	22.239498728689632
2005	16.125266926783343
2006	15.208671671904202
2007	22.426021592720595
2008	16.466327611266784
2009	19.52851713168021
2010	23.13921327956857
2011	23.00246462741321
2012	25.299245626643568
2013	24.29660814362204
2014	23.587818698622584
2015	21.22940280797386
2016	20.016243582261257
2017	19.436379810206777
2018	22.692249378725627
2019	21.235745720472337
2020	19.5963040631031
2021	19.321203808020336
2022	17.151919285679476