At the moment, there are about 20 boats in the harbor here in Pago Pago (pronounced "Pongo Pongo" for those of you that aren't aware of it), American Samoa. A rough breakdown is 20% Catamarans, 1 monohull way too big for a vane and about 2/3 of the rest (including a couple with sugar scoop sterns) have wind vanes.
That's just one harbor at one point in time, but the impression I have of what I've seen while out here pretty much matches what's in the harbor at the moment.