Results for this survey are reported for the period July to September 2021 compared with 2019 and 2020, as well as the quarterly averages for these periods.
Adroddir ar ganlyniadau'r arolwg hwn ar gyfer y cyfnod rhwng Gorffennaf a Medi 2021 o gymharu â 2019 a 2020, yn ogystal â'r cyfartaleddau chwarterol ar gyfer y cyfnodau hyn.