Year	% of revenue
1998	16.541958837462957
1999	16.973532554734273
2000	19.96263535611708
2003	40.32324561114125
2008	25.08451814179507
2009	28.28830918031333
2010	32.923255388097786
2011	21.234384093529243
2012	27.919922574701694
2013	39.268433381906654
2014	26.93023246561781
2015	24.103961458686474
2016	28.40038851456453
2017	35.84902305132835
2018	29.48727987645517
2019	34.5267578153942
2020	36.05182720145992
2021	34.128975080819366
2022	31.61618918079634