Year	% of revenue
1998	20.416628072986725
1999	20.69303811792075
2001	20.918027162644883
2002	20.716434061649615
2003	20.4433899693527
2004	19.78662258426095
2005	20.110036805283595
2006	19.867308018399154
2007	19.821979346991956
2008	21.261049232239817
2009	21.46158853497849
2010	21.256623850883543
2011	21.81936746005869
2012	21.188002610943357
2013	21.434407856027725
2014	21.512131090864077
2015	23.10780789135172
2016	22.43598337578764
2017	22.75036496350365
2018	24.151420240361134
2019	23.498835687821558
2020	24.434007903702202
2021	25.117340763707496
2022	27.17755611113173