Year	% of revenue
1990	24.31525284189858
1991	26.510454217736125
1992	22.54693665177991
1993	20.7569814413676
1994	16.64617707322334
1995	13.307413488645869
1996	13.85581009776702
1997	16.582147275503495
1998	17.316844219350333
1999	16.082741854068587
2001	9.838655185952867
2002	12.634094013907179
2003	12.024194658590307
2004	10.10654830728681
2005	10.643831123190104
2006	17.047594621331477
2007	15.743697528838712
2008	12.589324773821811
2009	10.889442710842111
2010	9.24512381574798
2011	15.555691605098797
2012	21.672551524817678
2013	17.34529683694187
2014	34.567844509173014
2015	34.627928104670765
2016	32.694666547406605
2017	33.2564096068506
2018	30.474903355412003
2019	31.19242921926625
2020	30.294681994077166
2021	26.54385153393385
2022	30.757432976298173