Year	% of revenue
1990	56.498049656368025
1995	46.670997076973045
1996	49.496221662468514
1997	53.19903303787268
1998	46.441947565543074
1999	36.24460645737241
2009	23.056804733727812
2010	15.829399764284988
2011	15.093625874787215
2012	16.388965378783286
2013	16.28389418016947
2014	14.69346159729043
2015	10.976668855586325
2016	10.711935781072913
2017	10.890902983441759
2018	9.517618231417853
2019	8.090160208879896
2020	7.940084567451647
2021	7.074240841528343