The statistics in this release are based on information collected in the fourth SWAC collection and are published as official statistics in development (ONS).
Mae’r ystadegau hyn yn seiliedig ar wybodaeth a gasglwyd ym mhedwerydd casgliad y CBGY ac, fel y cyfryw, cânt eu cyhoeddi fel ystadegau swyddogol dan ddatblygiad (SYG).