However, COVID-19 disruption has resulted in a gap in data for 2019/20, the year when administration of the assessments was most impacted by the pandemic.
Nid oes digon o ddata ar gyfer 2019/20, y cyfnod yr effeithiwyd arno fwyaf gan y tarfu yn sgil pandemig COVID-19; mae'r siart felly yn dangos data ar gyfer dwy flynedd yn unig.