Over the longer term, the rate has decreased by 3.0 percentage points over the last five years and by 4.3 percentage points over the last decade.
Dros y tymor hirach, mae’r gyfradd wedi gostwng 3.0 pwynt canran dros y pum mlynedd diwethaf, a 4.3 pwynt canran dros y degawd diwethaf.