Year	% of revenue
2002	26.840904319938048
2003	31.85473125875043
2004	32.51111673984015
2005	31.278947411378304
2006	32.937967418053944
2007	32.232523418938676
2008	32.138727742989566
2009	31.185824741692407
2010	29.790071621763474
2011	29.842652886627903
2012	29.854723735498244
2013	32.78707623172542
2014	33.319091927046706
2015	33.81687367825976
2016	36.084504576681084
2017	36.8945167456754
2018	38.614079437343484
2019	36.717230119441524
2020	37.392735679084296
2021	38.16960953117665