Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
Thus Sicily even from the Carthaginian period formed a closed customs-district, on the frontier of which a tax of 5 per cent on the value was levied from all imports or exports; thus on the frontiers of Asia there was levied in consequence of the Sempronian law(10) a similar tax of 21 per cent; in like manner the province of Narbo, exclusively the domain of the Roman colony, was organized as a Roman customs- district This arrangement, besides its fiscal objects, may have been partly due to the commendable purpose of checking the confusion inevitably arising out of a variety of communal tolls by a uniform regulation of frontier-dues. The levying of the customs, like that of the tenths, was without exception leased to middlemen.
10. Cf. IV. III. Jury Courts
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Reference address : https://www.ellopos.net/elpenor/rome/4-11-commonwealth-economy.asp?pg=11