I can give you a couple of answers that could help.
The first is that, based on labour force survey data, 43% of Canadian students of the slightly over two million students in Canada over 15 with income over $5,000 would have been working in February. A very significant portion of post-secondary students are eligible for the CERB, and are applying for the CERB, because they would have ceased working as a result of measures due to COVID.