This statistical release is published quarterly (with releases typically occurring in January, April, July and October) and covers the preceding 3 months.
Cyhoeddir y datganiad ystadegol hwn bob chwarter (cyhoeddir datganiadau fel arfer ym mis Ionawr, mis Ebrill, mis Gorffennaf a mis Hydref) ac maent yn cwmpasu'r 3 mis blaenorol.