Global sales for english music is not evenly distributed so extrapolation estimates by population are misleading; English music sales are skewed towards USA,UK,Canada and Australia for obvious reasons.
A country like. Japan while a large music market in its own right,favour their own artists over international acts(such a distincition for Zeppelin is not made in the english speaking countries). Brazil may have 6X times the population Canada but the latter is a much bigger market for groups like Zeppelin and Floyd(Remember music is very expensive in Latin America in real terms)