However, as the Annual Population Survey (APS) provides quarterly results, it is useful to use the APS to look at trends in the Welsh language between censuses.
Gan fod yr Arolwg Blynyddol yn darparu canlyniadau chwarterol, mae'n ddefnyddiol i’w ddefnyddio i edrych ar dueddiadau’r Gymraeg rhwng cyfrifiadau.