January to December 2020 year to date average, at 52%, saw a fall of 5 percentage points on 2019 and 3 percentage points on 2018.
Gwelodd cyfartaledd Ionawr i Ragfyr 2020 hyd yma, ar 52%, cwymp o 5 pwynt canran ar 2019 a 3 phwynt canran ar 2018.