Year	% of revenue
1990	14.38986383704968
1991	16.070238701838278
1992	24.289498419208748
1993	31.675071766622704
1994	31.61645891043398
1995	31.357854255004437
1996	32.31691602349335
2004	42.360638117856745
2005	41.77920931297211
2006	42.22242928442962
2007	29.411298266278546
2008	38.686110261580914
2009	34.64347765449431
2010	40.356669485281905
2011	44.160138677990716
2012	43.72377392552196
2013	48.3547333863243
2014	44.48405368693516
2015	44.01821426842217
2016	42.60530931955604
2017	43.07101535540708
2018	45.832448445714554
2019	46.52901080905967
2020	39.329828541759014
2021	32.67188212309324