The value for July to September 2019 will have already been subject to some of this downward revision, whereas the equivalent figure for July to September 2021 will not yet.
Bydd gwerth Gorffennaf i Fedi 2019 eisoes wedi bod yn destun rhywfaint o ddiwygio am i lawr, ond nid yw’r ffigur cyfatebol ar gyfer Gorffennaf i Fedi 2021 wedi cael ei ddywygio eto.