Year	% of revenue
1985	31.434149804756835
1986	34.43997317236754
1987	41.01169431601849
1988	50.60643564356435
1989	44.189339536765445
1993	48.94441069258809
1994	46.05242000321595
1995	45.49864726187145
1996	40.60387957517774
1997	41.3703587161737
1998	42.294961382861345
1999	38.16859504132231
2000	40.97837646224743
2005	16.535587118905934
2006	11.472183596062617
2007	14.862883461264525
2008	12.390180273258213
2009	11.898467709335794
2010	17.978991872018348
2011	23.93020022210993
2012	20.90270895097796
2013	7.881415346736932
2014	6.423699579687596
2015	5.210362208048628
2016	5.096587010220314
2017	3.8389505635852452
2018	3.7965651073059568
2019	3.7557837996793735
2020	3.43642302749113