I think that in proportional representation countries, the voter turnout tends to be between 70 and 80%, and in FPTP countries—I don't know the figures for Canada—it's more like 60%. The normative aspect of compulsory voting is, of course, that one cannot impose any compulsion to vote even when voters have to, quote-unquote, “vote”—
On August 22nd, 2016. See this statement in context.