Year	% of revenue
2000	43.36698443883677
2001	45.770735629404136
2002	45.0462122798381
2003	36.94201948447202
2004	41.86425739394319
2005	39.59406005897173
2006	15.346765733303434
2007	32.39147187259183
2008	30.28872479439456
2009	29.21422312329514
2010	30.036637850579435
2011	31.13396765173746
2012	34.83880834608734
2013	29.966485660953673
2014	37.401841977702375
2015	44.37617693562143
2016	51.05241989542834
2017	48.14014598540146
2018	46.47055378462723
2019	43.93017732794676
2020	39.27324005084819