Good question.
Before the 2021 census, we asked the entire population a question on mother tongue, which is one of the criteria set out in the Canadian Charter of Rights and Freedoms. However, we didn't have any information on the other criteria. Since 2021, we've been asking new questions on language of instruction. These questions help to provide a full and detailed picture of the population of children eligible for instruction in the minority official language.
We also have other sources of enrolment data, for example. For some time now, we've been collecting data each year on enrolment in minority‑language programs in Canada outside Quebec. We had already noted the trends along these lines in the past. However, since the 2021 census, we've been collecting information in much greater detail.