In Wales the gap widened by 0.9 percentage points and in the UK, it has narrowed by 0.2 percentage points compared to the previous year.
Yng Nghymru ehangodd y bwlch 0.9 pwynt canran, ac yn y DU roedd lleihad o 0.2 pwynt canran o'i gymharu â'r flwyddyn flaenorol.