Year	% of revenue
1972	17.391304347826086
1973	19.80392156862745
1974	12.65684669939989
1975	10.26086956521739
1976	10.781671159029651
1977	10.099064391854705
1978	10.529922338967564
1979	10.01418439716312
1980	7.23620987891601
1981	4.831795393446196
1982	4.721030042918455
1983	4.261491844497453
1984	3.3165990173039948
1985	3.2338919742468177
1986	4.872444194335022
1987	8.25229006093378
1988	5.5961474593158425
1989	6.046127934554704
1990	6.394126270029823
1991	5.073676765295296
1992	5.253430743410011
1993	5.152881849497496
1994	6.081110263313226
1995	3.9981594786847734
1996	3.186434670890142
1997	2.7467793064013346
1998	4.407133761847031
1999	2.535102484098337
2001	3.107546056827764
2002	3.3276127933191137
2003	3.1818133347518742
2004	3.0199697031277206
2008	3.767988662494231
2009	2.203736740768323
2010	2.905956535022834
2011	4.4711145257627205
2012	3.711288659023304
2013	3.2986376589977064
2014	2.777576455501286
2015	2.2844017244956336
2016	2.2227204640417013
2017	2.318601865924072
2018	2.3470804209504212
2019	2.0594901347511763
2020	2.1969317064468856
2021	3.6312059932544076
2022	3.0219276337659915