Year	% of revenue
1990	33.015223812769825
1991	34.01988071570577
1992	38.112150809370945
1993	35.842175066313
1994	38.38759836026952
1995	36.44566061457679
1996	34.83421370839432
1997	33.83690938465463
1998	33.928862783488334
1999	33.275288092189506
2000	32.15255894816907
2001	32.49777878598839
2002	32.33468629984893
2003	31.096974833084428
2004	32.51111673984015
2005	33.881018043518864
2006	37.03892918145806
2007	37.85898330428554
2008	37.310629607342904
2009	37.9433010709878
2010	41.47121092916274
2011	39.6320792127141
2012	40.03297493554101
2013	40.67709025855504
2014	40.62102422074207
2015	42.09241157504458
2016	41.735439242430765
2017	42.59794072705679
2018	45.73115229947036
2019	47.46473999033847
2020	34.458915127476445
2021	39.2679975097105