Year	% of revenue
2008	28.71853851895439
2009	32.60805560533017
2010	30.269148093126134
2011	26.065779887808674
2012	26.53806995640096
2013	25.94349305103488
2014	24.68724592810955
2015	24.82893199800951
2016	24.63536110320699
2017	24.536839028692125
2018	23.083992487916326
2019	25.255307218681587
2020	23.839939176243135
2021	22.317302844433215