4. Where maximum charges under Articles 8 to 11 are denominated in currencies other than the euro, the values shall be determined in those currencies by applying the average of the reference exchange rates published on 15 January, 15 February and 15 March of the relevant calendar year by the European Central Bank in the Official Journal of the European Union. For the maximum charges, the limits in currencies other than the euro shall be revised annually as from 2023. The annually revised limits in those currencies shall apply from 15 May.