Swansea Bay health board saw the highest proportion spending less than 4 hours in emergency departments (78.1%), and Cardiff and Vale saw the lowest (63.7%).
Bwrdd Iechyd Bae Abertawe welodd y gyfran uchaf yn treulio llai na 4 awr mewn adrannau achosion brys (78.1%), ac ym Mwrdd Iechyd Caerdydd a’r Fro oedd y gyfran isaf (63.7%).