Year	% of revenue
1990	3.1314768465063576
1991	2.3288514134775786
1992	2.14106563895516
1993	2.478123723702848
1994	2.813367666426891
1995	2.30205020675175
1996	2.206193815597496
1997	2.1127771483808204
1998	1.7896845747033627
1999	2.1380461152188133
2000	2.293347357484705
2001	2.2770237844594856
2002	2.2621610101377754
2003	2.326227796638295
2004	2.3073966410892583
2005	2.220145780729663
2006	2.010480199295593
2007	1.96470921647301
2008	2.1058837800402275
2009	2.7146688209446497
2010	2.8665880376726456
2011	2.8330272273254367
2012	2.78788093443719
2013	2.913155808390317
2014	6.178301896126152
2015	6.284423377414465
2016	6.718069819269977
2017	7.0370705690469135
2018	6.807349298751516
2019	6.878432264244314
2020	7.304410949747188
2021	5.902176282204094
2022	5.4159431139803536