As part of the development work for these household estimates, the WaSP working group agreed to the use of 2001, 2011 and 2021 Census data as the historical basis for household membership rates.
Mae canlyniadau’r cyfrifiad ar gyfer 2001, 2011 a 2021 wedi’u cynnwys ar y siart uchod, er mwyn dangos y gwahaniaethau rhwng y cyfrifiad a’r Arolwg Blynyddol yn yr un cyfnod.