Due to the COVID-19 pandemic, the National Survey switched to telephone mode in May 2020, with monthly results available for each of May to September 2020.
Oherwydd pandemig COVID-19, cynhaliwyd yr Arolwg Cenedlaethol dros y ffôn ym mis Mai 2020, gyda chanlyniadau misol ar gael ar gyfer pob mis o fis Mai i fis Medi 2020.