Year	% of revenue
1998	8.008570708343838
1999	8.999600209121382
2000	7.1032317034543295
2001	7.46130746130746
2002	12.53525404607975
2003	11.241784849533033
2004	14.43753759775416
2005	13.616743443723022
2006	15.348489380795694
2007	10.82718584429741
2008	9.753896821637229
2009	12.300524793830995
2010	11.66853467179962
2011	10.35745450708198
2012	10.116258878932117
2013	10.5460469498312
2014	11.569051839588914
2015	10.505199393501279
2016	10.467414752377657
2017	10.858868411555589
2018	11.04239748397242
2019	11.436915013103706
2020	12.088281963744771
2021	11.074827718446038