Year	% of revenue
1990	36.12750885478158
1991	34.00990099009901
1992	36.55970541820095
1993	40.84051724137931
1994	39.617768595041326
1995	41.85932120019675
1996	39.25657298277425
1997	39.132165605095544
1998	36.44925008719916
1999	37.9492600422833
2000	37.8941524796447
2001	38.51491183063769
2002	40.55183009778659
2003	41.190122798808886
2004	40.17985768542367
2005	40.829634375143
2006	40.72877703411518
2007	23.972995306319202
2008	16.745714455795042
2009	15.228638202580063
2010	16.426430490460987
2011	16.281909203578522
2012	16.249459627754444
2013	16.78230711852082
2014	19.533289249295237
2015	22.215313717243017
2016	16.21057738961669
2017	17.63320191725695