Year	% of revenue
1990	24.729515617926666
1991	28.035842889590608
1992	28.458370011127904
1993	29.967378868927984
1994	25.221880449050765
1995	28.950238038245697
1996	25.902383711019816
1997	20.584756117340483
1998	16.533491898836367
1999	18.258598116457488
2000	18.325961618215242
2001	17.45475304686968
2002	16.687575824418218
2003	16.649785742111415
2004	17.34629109835395
2005	17.51961745953899
2006	20.315078969652607
2007	19.99442475181076
2008	22.19044622537822
2009	19.616130838907978
2010	21.461076079568926
2011	19.500261123493022
2012	18.98497397856195
2013	17.796704640362698
2014	19.36734639290208
2015	17.95691228310179
2016	18.051495938054764
2017	18.532694845813676
2018	20.924523781347432
2019	20.09522787068943
2020	18.829975752908126
2021	21.414862480843684
2022	24.335618318900384