The gap had widened over time between 2018/19 and 2022/23, from 2 to 5 months in Year 3, 4 to 9 months in Year 6, and 5 to 11 months in Year 9.
Roedd y bwlch wedi ehangu dros amser rhwng 2018/19 a 2022/23, o ddau i bum mis ym Mlwyddyn 3, pedwar i naw mis ym Mlwyddyn 6, a phum i un ar ddeg mis ym Mlwyddyn 9.