Swansea Bay health board saw the highest proportion spending less than 4 hours in emergency departments (76.0%), and Cwm Taf Morgannwg saw the lowest (63.2%).
Bwrdd iechyd Bae Abertawe welodd y gyfran uchaf yn treulio llai na 4 awr mewn adrannau achosion brys (75.3%), ac yng Nghwm Taf Morgannwg oedd y gyfran isaf (64.6%).