Year	% of revenue
2000	11.721370164801268
2001	11.843360308127142
2002	14.342143017213754
2003	11.908910735660603
2004	17.158859506039235
2005	15.404779396593021
2006	16.21840674346975
2007	16.798827833956096
2008	16.49010673706425
2009	13.483677475625381
2010	14.892108542286733
2011	14.770003361889472
2012	21.90571913980875
2013	41.10706226648325
2014	39.88211974726036
2015	40.74103294904289
2016	40.946392925679135
2017	34.80105011251206