Historically, the survey has received response rates of between 14% and 17% (Y1: 14%, Y2: 16%, Y3: 17%, Y4: 16%).
Yn hanesyddol, mae'r arolwg wedi derbyn cyfraddau ymateb rhwng 14% ac 17% (Bl1: 14%, Bl2: 16%, Bl3: 17%, Bl4: 16%).