Year	% of revenue
1985	23.23393681221157
1986	21.143527833668678
1987	24.66684797389176
1988	24.084158415841582
1989	22.03904116516638
1993	20.39034021871203
1994	19.48866377231066
1995	21.19600709021364
1996	26.34073553936628
1997	24.952800503461297
1998	28.92975358587716
1999	26.327272727272728
2000	21.276143211627083
2005	34.618231426101225
2006	39.552901845573615
2007	24.782320573149324
2008	35.35071419570691
2009	22.792327658011498
2010	17.17465340836108
2011	13.883963970969399
2012	18.89739590577155
2013	17.785384772600466
2014	13.189347331083336
2015	14.500165128777152
2016	15.912572063750046
2017	11.458191790956352
2018	14.541047564594752
2019	12.063042587827248
2020	16.04458870678048