Over the longer term, the rate has decreased by 1.6 percentage points over the last five years and by 4.1 percentage points over the last decade.
Dros y tymor hirach, mae’r gyfradd wedi gostwng 1.6 pwynt canran dros y pum mlynedd diwethaf, a 4.1 pwynt canran dros y degawd diwethaf.