Year	% of revenue
1981	3.1909788867562376
1982	3.236836106678824
1983	1.7750257997936016
1984	2.3729446935724963
1985	2.0605160571746794
1986	3.740936058009229
1987	3.725015142337977
1988	5.190530446892012
1989	5.891271388347412
1990	5.6876751966723935
1991	7.338775510204082
1992	11.391767415083477
1993	9.364686468646864
1994	13.969097054563012
1995	20.730782278253248
1996	21.770510687272697
1997	22.09028818317821
1998	18.951761950622178
1999	17.904260433203046
2000	13.89855121737523
2001	12.537572901960791
2002	10.92486399058962
2003	11.1691805101013
2004	11.89723904951181
2005	11.356182195620447
2006	10.631539219231287
2007	10.223221097784526
2008	9.654828876859108
2009	10.668650826795428
2010	10.137020489940411
2011	10.307960092043968
2012	10.407312107026737
2013	10.469802185004218
2014	9.456698288197634
2015	8.024713815181627
2016	7.615521575688443
2017	6.656814214972918
2018	6.0050319354405035
2019	5.7464807363878325
2020	5.932292610883517
2021	6.063943419808231
2022	7.137230960580846