Year	% of revenue
1990	5.423135797069757
1991	5.487674169346195
1992	4.883820998278829
1993	4.84214603912454
1994	6.185787671232877
1995	4.660932186437288
1996	5.477528089887641
1997	4.930448222565688
1998	7.141374299356445
1999	5.218525766470972
2000	3.3987840127578988
2001	4.774706957737391
2002	4.193647856922603
2003	3.752982198568545
2004	4.259792851024064
2005	0.4523154241952854
2006	0.5207823695054199
2007	0.5091571970189971
2008	0.6535581573394581
2009	0.6545744095364114
2011	0.6697715247385705
2012	0.7429907114929647
2013	0.5378208397076322
2014	0.4858407051001945
2015	0.5807604730308743
2016	0.2562790523078678
2017	0.2133194964250709
2018	0.26700753897463675
2019	0.8602211081700565
2020	0.31874095435288297