Over the longer term, the rate has decreased by 0.9 percentage points over the last five years and by 4.5 percentage points over the last decade.
Dros y tymor hirach, mae’r gyfradd wedi gostwng 0.9 pwynt canran dros y pum mlynedd diwethaf, a 4.5 pwynt canran dros y degawd diwethaf.