Swansea Bay health board saw the highest proportion spending less than 4 hours in emergency departments (76.2%), and Cwm Taf Morgannwg saw the lowest (61.4%).
Bwrdd Iechyd Bae Abertawe welodd y gyfran uchaf yn treulio llai na 4 awr mewn adrannau achosion brys (79.1%), a Chaerdydd a’r Fro welodd y gyfran isaf (61.7%).