Year	% of revenue
1991	9.657534246575343
1992	12.889364388943456
2009	4.98288031019377
2010	4.131280631460645
2011	3.817137220373278
2012	3.586209877101728
2013	4.24086879887645
2014	4.124527826067482
2015	6.28182082607575
2016	8.008128711530262
2017	7.528570116439309
2018	10.547735857142444
2019	7.98549286756141
2020	8.342091961557266
2021	9.369280103024654
2022	10.85367596220722