The data is provided by local authorities to the Office for National Statistics (ONS) on a monthly basis, and from the ONS to the Welsh Government on a six-monthly basis.
Darperir y data gan awdurdodau lleol i’r Swyddfa Ystadegau Gwladol bob mis, a chan y Swyddfa Ystadegau Gwladol i Lywodraeth Cymru bob chwe mis.