Year	% of revenue
2005	2.5741188475396988
2006	2.989873125224598
2007	2.445452074197485
2008	1.9624712601053178
2009	1.9237729554502967
2010	2.4803851083117125
2011	2.6176470588235294
2012	3.168662112090671
2013	3.4195668719161505
2014	3.631762231244852
2015	4.171519869580524
2016	4.286857329829152
2017	4.922563058112063
2018	4.277480240776765
2019	4.062627066696803
2020	4.284339669740149
2021	4.210809761125589