Due to the changes in methodology and the impact of the COVID-19 pandemic, the survey results for 2021 have been labelled as ‘experimental statistics’ (Office for National Statistics).
Oherwydd y newidiadau mewn methodoleg ac effaith pandemig COVID-19, mae canlyniadau’r arolwg ar gyfer 2021 wedi cael eu labelu fel ‘ystadegau arbrofol’ (Swyddfa Ystadegau Gwladol).