Year	% of revenue
2001	28.160203172576033
2002	29.589238086756097
2003	27.939791057520395
2004	22.23320943659892
2005	23.812234592767144
2006	22.57547223742822
2007	23.968155624950313
2008	22.68024906078949
2009	24.192265304063238
2010	22.798936196496495
2011	19.051240757335265
2012	21.42757953836711
2013	23.62110991883622
2014	23.606499935511028
2015	15.048393461608745
2016	15.189180737961225
2017	13.906477081565912
2018	11.80091447369786
2019	14.30370583110123
2020	19.710643530273064
2021	20.42881903749455