Year	% of revenue
1991	20.831445971110778
1992	22.571421341633137
2009	14.036317863606904
2010	8.650476373968429
2011	7.500917423022205
2012	9.49948207854234
2013	6.9516607142750955
2014	7.909473046603354
2015	9.24441620731431
2016	8.977679171724432
2017	8.456427389716463
2018	7.658963663406318
2019	8.120864563826068
2020	8.342926236646774
2021	9.209814861661213
2022	7.8751247658675645