Year	% of revenue
2004	7.976722390205213
2008	8.447816503960116
2009	7.845053278271627
2010	5.9500579942648395
2011	5.568616639890443
2012	2.940806338678449
2014	1.213859024075989
2015	5.088923783084159
2016	0.6883692412932433
2017	1.3253701360502976
2018	1.3485108566162634
2019	2.7083379936623295
2020	1.3227678724752705
2021	4.211869145392756