This has meant a slight revision to the percentage of the population aged three or older who can speak Welsh fluently for 2019-20, and some revisions to the data for 2013-15.
Mae hyn wedi arwain at wneud diwygiad bach i ganran y boblogaeth 3 oed a throsodd a all siarad Cymraeg yn rhugl ar gyfer 2019-20, ac ambell ddiwygiad i'r data ar gyfer 2013-15.