Year	% of revenue
2009	26.383032074996756
2010	26.238793480694916
2011	27.436738508065346
2012	29.49148291137807
2013	28.930759998787032
2014	31.478888374163965
2015	33.50890258339621
2016	36.46789476853275
2017	33.2564096068506
2018	33.46869142241128
2019	32.229040757585096
2020	32.26815975995771
2021	34.09172451117665