The majority of the year two TSW survey (collecting 2019 data) remained the same as the previous year (which collected 2017 and 2018 data).
Roedd y rhan fwyaf o arolwg blwyddyn dau TSW (gan gasglu data 2019) wedi aros yr un fath â’r flwyddyn flaenorol (a gasglodd ddata 2017 a 2018).