Just as a small correction, there actually have been two abuse of dominance cases over the last five years, one with the Toronto Real Estate Board and the other with the Vancouver Airport Commission.
I do not have any sort of empirical sense of how much enforcement is taking place elsewhere, but I did read an article that said it's being enforced in the United States at a rate of 10:1 by private entities versus a public enforcer. You could extrapolate from that how much you would expect to see in Canada.
Again, I don't know if the budgetary constraints in the United States, for example, are quite as severe as they are in Canada, so even the numbers of publicly brought abuse of dominance proceedings, I would guess, are higher on a per capita basis in the United States.