Year	% of revenue
1999	31.82087562406877
2000	28.799480791847852
2001	25.520716722201005
2002	37.10967450579067
2003	30.397879830428405
2004	27.430556962099196
2005	17.72001326721782
2006	19.144360673986743
2007	19.239816050461314
2008	15.6993905417171
2009	23.12807567259619
2010	20.289034637251017
2011	19.504229126538817
2012	21.014351649623972
2013	25.192933353082083
2014	26.115786816637264
2015	21.418712190348206
2016	26.47794457443528
2017	22.91992267829234
2018	21.933480196867837
2019	22.380958896706677
2020	21.915870844673186
2021	20.01548681222581
2022	14.76589660631184