Year	% of revenue
1990	11.677933002854138
1991	7.914226804123711
1992	12.347547325250282
1993	11.985650498034577
1994	12.971416716055625
1995	18.745413585857985
1996	14.230723285552127
1997	14.0042276193004
1998	16.86307896820062
1999	15.45727244443854
2000	14.697275605255248
2001	14.797618426231452
2002	19.904952684499698
2014	7.857684210526315
2015	10.318953859795279
2016	11.903047267353852
2017	13.231165973485068
2018	13.15718654975438
2019	15.355041680894821
2020	17.861057349955505
2021	16.22690532095766
2022	13.876738512308751