Year	% of revenue
1999	38.26723607989565
2000	30.414615212837226
2001	34.4460016733877
2002	36.207811602014836
2003	36.25663126432515
2004	37.87913607534213
2005	35.40493765843936
2006	35.427993813277304
2007	37.116022116998984
2008	33.83898127223549
2009	35.57089144046048
2010	36.06101693840944
2011	33.55101109503042
2012	34.400916206828015
2013	36.01824364542435
2014	30.005532776970185
2015	26.543911638946778
2016	18.117290933921065
2017	18.937153021085773
2018	20.22906282335652
2019	21.838142012376302
2020	21.804703365039614
2021	21.515434753848023
2022	19.387219072886293