Cardiff, Swansea, Rhondda Cynon Taf, Carmarthenshire and Caerphilly had the highest volumes of motor vehicle traffic.
Gwelwyd y lefelau uchaf o draffig cerbydau modur yng Nghaerdydd, Abertawe, Rhondda Cynon Taf, Sir Gaerfyrddin a Chaerffili.