Year	% of revenue
2000	27.134429316546182
2001	29.085569371474058
2002	22.53475109274568
2003	21.52901238201762
2004	21.40832761152893
2005	24.031021404914366
2006	22.797609852284978
2007	24.781263601423
2008	28.14665948839809
2009	28.39696636559888
2010	26.561917826798272
2011	28.800271334458454
2012	27.12830501323903
2013	25.267325951712433
2014	22.76991135188804
2015	22.701407311709186
2016	24.261564720971272
2017	22.694395828124442