Those recorded as ‘0’ include a combination of businesses who had already completed the survey before they were called as well as those for whom a telephone number could not be found.
Mae'r rhai a gofnodwyd fel '0' yn cynnwys cyfuniad o fusnesau a oedd eisoes wedi cwblhau'r arolwg cyn iddynt gael eu galw yn ogystal â'r rhai nad oedd modd dod o hyd i rif ffôn ar eu cyfer.