The data in this report are provisional estimates for October 2020 to September 2021 and will be revised routinely over the next 18 months to account for late returns.
Amcangyfrifon dros dro yw'r data yn yr adroddiad hwn ar gyfer Hydref 2020 i Medi 2021 a chânt eu diwygio fel mater o drefn dros y 18 mis nesaf i gyfrif am ffurflenni hwyr.