Year	% of revenue
2008	8.210005976008713
2009	8.70813290914648
2010	7.787974219980308
2011	8.172979706980087
2012	7.516912821201317
2013	7.995007994287782
2014	7.64564340693538
2015	7.959758190381029
2016	8.03879416034327
2017	9.549041738552363
2018	8.656081764001662
2019	9.12671828261334
2020	8.800300570614526