Year	% of revenue
2000	47.380941252357076
2001	45.22223864836238
2002	46.485306837959484
2003	50.303369243146726
2004	51.65612915576862
2005	52.94934552957614
2006	53.017182655215045
2007	50.2138835847045
2008	45.52617535943871
2009	48.46197023517805
2010	44.91822072504305
2011	45.74768816927373
2012	39.23330446795178
2013	24.926092901753766
2014	25.540535898581652
2015	25.70932652195781
2016	26.81896643169172
2017	29.18348394470836