Year	% of revenue
1990	37.44785935460757
1991	28.052847846352964
1992	30.518633076554803
1993	18.33318649171979
1994	26.8552652121723
1995	22.448447741795018
1996	47.4629591174562
1997	50.368421052631575
1998	31.671132605712042
1999	35.908696595098675
2003	29.572173257304833
2004	31.490150665241828
2005	29.508128964790263
2006	32.76052128754103
2007	28.71155278630396
2008	31.875183190458152
2009	28.269240130901192
2010	29.790071621763474
2011	23.912359791816463
2012	29.80191599878455
2013	38.13797258684021
2014	42.64534595444204
2015	32.43684227764585
2016	27.85680558686863
2017	36.8945167456754
2018	38.00425931737501
2019	35.33944180674409
2020	29.152025391212028
2021	22.640119081175115