Year	% of revenue
1983	13.719052564575026
1984	10.360838821280083
1985	15.921668795232014
1986	15.2225253938046
1987	15.804315158711018
1988	13.460156858049452
1989	8.961951650407244
1990	9.396524907790074
1991	5.858961374775924
1992	11.669447312175107
1993	9.139242668652638
1994	8.520123536751246
1995	13.882826559665917
1996	11.219065194983877
1997	13.831281784115536
1998	13.006660953186099
1999	11.021404431092753
2000	12.017955993859609
2001	10.784598309570564
2002	10.855591101852541
2003	12.604176912232386
2004	11.77289485326648
2005	10.887703973634148
2006	11.411072797114132
2007	11.77128406677785
2008	12.016279965075986
2009	16.33232087500093
2010	13.5913093329247
2011	13.452486492815682
2012	13.723381339241753
2013	38.77266491477249
2014	12.069506373545575
2015	15.442502119399101
2016	12.88969199992531
2017	14.950126458277877
2018	13.785410611013596
2019	10.353152453526185
2020	13.09488905395261
2021	9.80725725955846