I would think it depends on the route. But remembering for airlines not all routes are equally profitable.

For example Air NZ probably has a much higher proportion of airpoints customers on domestic routes (the most profitable) despite some fares being non-mileage earning. This is simply due to nearly everyone having loyalty cards (eg flybuys) which means NZ points. Whereas on longer haul the proportion will probably be lower as some will have other FFPs (still costs NZ as they have to pay the other FFP) and some wont bother (eg irregular leisure traveller).