Year	% of revenue
1997	16.74128720401221
2002	13.020771911915887
2003	12.633678513543042
2004	12.029794028120179
2005	11.10841937503265
2006	10.533352979530225
2007	9.596909886331709
2008	8.054414673813007
2009	8.411182373207467