Year	% of revenue
2008	25.68492465847218
2009	24.75440688758093
2010	23.298913765477142
2011	22.14739687968974
2012	22.437973167219326
2013	22.93322700522353
2014	24.11188879407539
2015	24.82893199800951
2016	24.827689955578748
2017	24.29088192308582
2018	24.781412709675184
2019	25.255307218681587
2020	23.3686175867276
2021	22.317302844433215
2022	20.354495282686365