Year	% of revenue
1990	7.448368927481812
1991	13.211686701525524
1992	12.472404888360572
1993	11.549107333481992
1994	9.316952879140246
1995	10.450412691759976
1996	9.530305750014959
1997	10.137133823696919
1998	9.728794337335263
1999	9.898926507018993
2000	9.763797870318717
2001	10.293927271234658
2002	10.18254420992584
2003	9.822269567167528
2004	9.470385093860136
2005	8.671744997111645
2006	7.961545349064671
2007	7.710838987021367
2008	9.003429103408887
2009	10.388937134256258
2010	9.373335889862108
2011	9.152211130353766
2012	9.365347890260086
2013	9.775168852612612
2014	10.028359272818507
2015	11.508668457245353
2016	12.08834060977058
2017	11.772092005661241
2018	11.493001063602282
2019	11.305064575557552
2020	12.175163564133811
2021	9.690948972780586