Some of the decrease may relate to mitigation activities during the end of the previous year (2019 to 2020) but it’s difficult to identify this from the data.
Gall rhywfaint o'r gostyngiad ymwneud â gweithgareddau lliniaru yn ystod diwedd y flwyddyn flaenorol (2019 hyd 2020) ond mae'n anodd nodi hyn o'r data.