Taking that into account, the 7 day rolling average has generally decreased since early January 2021 but has plateaued since early April 2021.
O ystyried hynny, mae'r cyfartaledd treigl 7 diwrnod wedi gostwng yn gyffredinol ers dechrau mis Ionawr 2021 ond mae wedi bod yn wastad ers dechrau Ebrill 2021.