The local authorities with the lowest number of Welsh speakers were Blaenau Gwent (4,000), Merthyr Tydfil (5,100) and Torfaen (7,400).
Yr awdurdodau lleol â’r niferoedd isaf o siaradwyr Cymraeg oedd Blaenau Gwent (4,000), Merthyr Tudful (5,100) a Thorfaen (7,400).