Year	% of revenue
1995	26.327752102432
1996	31.7714827514547
1997	32.099611871615494
1998	30.136414788790383
1999	30.654409442602244
2000	32.90370582608173
2001	27.404087913171466
2002	27.97404307471626
2003	26.369495278211758
2004	24.139914623252114
2005	22.732511804580756
2006	19.08373772053146
2007	20.695097077119144
2008	21.810102094877013
2009	21.728633024742336
2010	18.305351091755984
2011	15.862255573481256
2012	16.74448339016497
2013	17.17622912831816
2014	18.437065115033647
2015	20.42658856406509
2016	18.459081568837664
2017	18.700454630297514
2018	20.54177323058172
2019	19.040035892135332
2020	21.09036423540087
2021	20.82773840405256