Year	% of revenue
1997	18.477148949792024
2002	9.893570582758773
2003	7.6451329866363
2004	7.875729684200044
2005	7.019124599290566
2006	6.247527363840169
2007	6.681266528693879
2008	6.4768698294783045
2009	6.00145828536342
2010	6.346205531237656
2011	5.600548521663265
2012	5.761261292537373
2014	3.9535891913459267