Year	% of revenue
2005	29.78217438564566
2006	30.956069656142855
2007	28.662419112729275
2008	28.368315656752944
2009	30.557697452279413
2010	30.232721702978964
2011	29.984162895927604
2012	30.63816674558259
2013	28.5610547934741
2014	28.58423664125206
2015	28.02018846774384
2016	27.533670474356065
2017	27.489389072416532
2018	27.646076119038764
2019	30.628455552228996
2020	35.28619656787103
2021	32.322454732230874