Year	% of revenue
2010	35.9805640796043
2011	30.119053637602434
2012	26.39719647778921
2013	28.827486964686862
2014	23.600493060770212
2015	23.754347522073598
2016	20.59052098602107
2017	23.232375999843665
2018	21.36539594162528
2019	21.937256429805185
2020	21.64240551558944
2021	19.004756806225174