Year	% of revenue
1990	16.865116956933615
1991	18.01827487413424
1992	19.87782808473995
1993	20.83862855906768
1994	21.67485410965679
1995	20.959418250058643
1996	19.730464871724074
1997	19.09922402069278
1998	19.112083901458842
1999	19.036167710658315
2000	18.86618023785764
2001	20.28410268813489
2002	21.91016572963356
2003	22.09977208998071
2004	21.534981328396796
2005	21.426140617555642
2006	20.826877657910913
2007	21.0190975213424
2008	21.621999883938052
2009	23.243451131494954
2010	23.01971427761558
2011	22.492702026827317
2012	23.224454832158568
2013	23.750239595377508
2014	23.445652301930348
2015	23.259724655257603
2016	23.20294133048902
2017	21.8087638681901
2018	21.238132616133623
2019	22.073270231138906
2020	22.139203714363905
2021	21.717451868841426
2022	22.950461308449157