Increases in demand is reflected in the data in September 2020, around Christmas 2020, June 2021 and the end of summer 2021.
Mae’r galw uwch am brofion wedi’i adlewyrchu yn y data ym mis Medi 2020, tua adeg Nadolig 2020, mis Mehefin 2021 a diwedd haf 2021.