Year	% of revenue
2005	4.348703239209153
2006	4.350642012014362
2007	2.197387128292154
2008	3.4306633228054286
2009	3.248708066180443
2010	3.25995431737838
2011	3.318777802213272
2012	3.4344631468757605
2013	3.5640025905739026
2014	2.557567567302063
2015	3.237969552995142
2016	2.9209545812879063
2017	3.402099573319086
2018	2.7622144822387713
2019	2.903421948032214
2020	3.916151917542115
2021	3.441940425166802