Year	% of revenue
1990	43.59504420823265
1991	44.42155309033281
1992	47.316456241960864
1993	37.30258294316629
1994	36.80835217101567
1995	34.807127482917636
1996	29.950465757130058
1997	27.368270411276008
1998	25.86270204286093
1999	24.30446471725471
2000	23.422256305638903
2001	22.84027153110371
2002	19.678291491536974
2003	16.228057040126636
2004	16.555760638536096
2005	17.450564964484567
2006	19.433826752700973
2007	26.402049512949265
2008	24.021954393189965
2009	28.97707374819588
2010	28.30698486316402
2011	30.349782860428636
2012	31.222339626853618
2013	31.752318194679074
2014	29.23768409445133
2015	31.140698201008586
2016	32.322078068051724
2017	35.07158041984453
2018	34.36234132935216
2019	29.992522998055982
2020	31.92954467321012
2021	26.87311531397803
2022	28.75689709814207