Year	% of revenue
1991	51.53159340659328
1992	34.694009783911575
1993	33.68833378068395
1994	31.769684114624074
1995	29.565680436431208
1996	33.532158150641806
1997	30.433236941958548
1998	29.471887208430154
1999	32.892094463750695
2000	32.90210729347422
2001	31.856336173122298
2002	30.823662706195382
2003	30.19880227637347
2004	31.203294939902328
2005	31.208560413435688
2006	32.030720167603135
2007	31.348720054119173
2008	31.21818485047777
2009	33.6129591182516
2010	33.77754550602409
2011	33.66104471786508
2012	32.709354625218864
2013	31.481222622821104
2014	31.645124739738083
2015	30.62775567052928
2016	29.573249339168868
2017	29.398355043796908
2018	29.886001527201874
2019	28.658683613937715
2020	29.070245512261327
2021	27.84692322349568
2022	27.774211775272583