Year	% of revenue
2008	5.71586081411732
2009	4.485217012906108
2010	4.12716807180821
2011	4.538024771253809
2012	4.191011361877398
2013	4.840433517374368
2014	3.901666307208624
2015	3.9147265251838608
2016	3.429014774493143
2017	2.7680390178959002
2018	2.766228390209685
2019	2.8953042264979727
2020	3.4019009882515308