Year	% of revenue
1998	33.715300453306234
1999	34.08140486185467
2001	32.42535361190677
2002	32.399672867382705
2003	32.99330572598704
2004	34.167886299931276
2005	33.76867224703177
2006	33.134389683386026
2007	33.084862899998384
2008	31.79312630619522
2009	30.900971724877003
2010	31.53161527835126
2011	32.596231953619714
2012	32.58939887821578
2013	32.719997436534825
2014	32.90340969436081
2015	33.69510212167667
2016	34.272878914928974
2017	33.53595910860582
2018	33.59616580345982
2019	32.89676735146909
2020	33.033157022915255
2021	32.963395690628715
2022	32.20195619946384