Year	% of revenue
2001	24.829179240157988
2002	25.18764074813893
2003	32.359857671472355
2004	28.94877542980018
2005	27.4981392315089
2006	28.60587854351563
2007	28.1825696002066
2008	27.61461607072552
2009	28.75832227800652
2010	29.741042800864026
2011	30.96397245868569
2012	29.091388850086187
2013	28.594850964690654
2014	28.218709202658854
2015	31.285220886915173
2016	32.254534083802376
2017	49.16269086166739
2018	49.78097685859769
2019	48.84418682877214
2020	42.84671522550323
2021	43.21569444177251