The lowest numbers of people aged three years or older able to speak Welsh were in Blaenau Gwent (4,000) and Merthyr Tydfil (5,100).
Roedd y niferoedd isaf o bobl tair oed neu'n hŷn a oedd yn gallu siarad Cymraeg ym Mlaenau Gwent (4,000) a Merthyr Tudful (5,100).