Swansea Bay health board saw the highest proportion spending less than 4 hours in emergency departments (76.6%), and Cwm Taf Morgannwg saw the lowest (62.4%).
Bwrdd iechyd Bae Abertawe welodd y gyfran uchaf yn treulio llai na 4 awr mewn adrannau achosion brys (76.6%), ac yng Nghwm Taf Morgannwg oedd y gyfran isaf (62.4%).