considerable variation between the months of the year and the same months in different years with a 10.3% reduction in positive tests observed when compared to the 2015(r) data
amrywiad sylweddol rhwng misoedd y flwyddyn a'r un misoedd mewn blynyddoedd gwahanol gyda gostyngiad o 10.3% mewn profion cadarnhaol a welir o’i gymharu â data 2015(r)