The largest widening is between 2018/19 and 2020/21, though this is likely to be because there is a two-year time span between measurement points here, due to the COVID-19 pandemic.
Mae'r bwlch ar ei ehangaf rhwng 2018/19 a 2020/21, er bod y rheswm am hwnnw yn debygol o fod o ganlyniad i bandemig COVID-19, gan fod cyfnod o ddwy flynedd rhwng y pwyntiau mesur yma.