The July to September 2020 quarter had fallen significantly, down from 66 percentage points in 2019 to 29 percentage points in 2020, a decrease of 37 percentage points.
Roedd chwarter Gorffennaf i Fedi 2020 wedi gostwng yn sylweddol, i lawr o 66 pwynt canran yn 2019 i 29 pwynt canran yn 2020, gostyngiad o 37 pwynt canran.