However, the percentages have risen back to similar levels for the periods January to March 2021 and April to June 2021.
Fodd bynnag, mae’r canrannau wedi codi’n ôl i lefelau tebyg ar gyfer y cyfnodau mis Ionawr i fis Mawrth 2021 a mis Ebrill i fis Mehefin 2021.