Year	% of revenue
1997	29.84840686235414
2002	29.598739519967232
2003	33.49928369662196
2004	30.60904508214511
2005	28.286553524804177
2006	34.85266750316644
2007	32.41248039084688
2008	26.244863596293737
2009	35.84888967530744
2010	25.469628088242697
2011	29.97421049587328
2012	27.69491530836826
2014	39.856765064809295