Data from 17 March 2022 may not be directly comparable with earlier data as e-forms began to be sent to all new positive cases from that point.
Mae’n bosibl na fydd modd cymharu data o 17 Mawrth 2021 ymlaen yn uniongyrchol â’r data cynharach gan fod e-ffurflenni wedi dechrau cael eu hanfon i bob achos cadarnhaol newydd o’r pwynt hwnnw.