Year	% of revenue
1990	12.709160390309057
1991	13.457845020185788
1992	11.597026403486286
1993	11.071456280549304
1994	10.566712834718375
1995	12.358600870581938
1996	11.403496873431628
2004	10.120567574898748
2005	10.471371112782446
2006	10.303662622896974
2007	15.28682580932919
2008	11.786206080008093
2009	13.590209696913288
2010	14.685193485232395
2011	14.872596606995852
2012	14.298533750891373
2013	13.104143814913167
2014	11.034618293017795
2015	10.816291356963614
2016	9.80815045677115
2017	9.174214623647991
2018	9.94188513371395
2019	11.251109125972336
2020	16.309997949698772
2021	17.173875494479844