Year	% of revenue
1981	6.90978886756238
1982	6.496466833827216
1983	7.0588235294117645
1984	6.2593423019431995
1985	5.903100055689623
1986	6.361239288068557
1987	6.390066626287099
1988	5.431067223699203
1989	5.295646523716699
1990	5.796184103445158
1991	5.126530612244898
1992	7.210708117443869
1993	7.5553983969825556
1994	7.267020762916465
1995	10.293871244380137
1996	8.41638587682065
1997	4.732491030125107
1998	3.343709640718189
1999	3.2036415814429398
2000	2.691207613250501
2001	2.185079347711525
2002	2.0515575553883743
2003	1.9441294730016383
2004	0.42437441529485076
2005	-0.009986734058534792
2006	-0.0022362921313136977
2007	-0.0020439824549403057
2008	-0.00046181705633461785
2009	-0.0005168365505331861
2010	-8.313061010386062E-05