Year	% of revenue
1985	20.447284345047922
1986	18.846411804158283
1987	18.58852325265162
1988	12.425742574257425
1989	14.675836957621119
1993	10.768529769137302
1994	10.966393310821676
1995	11.736169418789066
1996	10.172913192311068
1997	10.163624921334174
1998	12.129459360058844
1999	14.750413223140496
2000	17.320099255583127
2005	13.238915215798006
2006	12.719472982108021
2007	16.56159731517082
2008	15.824495008648757
2009	21.12970159587674
2010	26.364594657932823
2011	31.463955768575058
2012	27.877762285547142
2013	29.922840724688797
2014	30.07255112255699
2015	28.84310717315865
2016	29.444586070209837
2017	31.356714824046534
2018	32.46739656457842
2019	30.18494675637491
2020	31.47879048802309