Year	% of revenue
1991	24.224438621103417
1992	16.360825832841638
1993	16.470757017586536
1994	16.600569633531656
1995	18.909981957513082
1996	18.58597791966402
1997	20.707625777334222
1998	20.69302819497163
1999	17.941020813479135
2000	17.729978061440733
2001	18.382128724238875
2002	16.809836723433072
2003	16.970188420081627
2004	15.472093535932366
2005	16.181390176171924
2006	17.910677039321765
2007	18.309947588347562
2008	16.91730451274455
2009	15.535017245971176
2010	14.76883738851049
2011	14.755006788415953
2012	14.681379702596109
2013	14.770153794610968
2014	15.215517032965842
2015	15.179283564105775
2016	16.695251238884413
2017	16.614833828536256
2018	15.906912018428388
2019	15.72799447473901
2020	16.300404010652976
2021	14.399657848962025
2022	16.474351871855884