Comparisons are made with April 2020 to March 2021, a period largely affected by the coronavirus (COVID-19) pandemic, when there were public health restrictions.
Gwneir cymariaethau â’r cyfnod Ebrill 2020 i Fawrth 2021, cyfnod a effeithiwyd i raddau helaeth gan y pandemig coronafeirws (COVID-19), pan roedd cyfyngiadau iechyd cyhoeddus mewn grym.