If there must be a "ranking", I'd like to add another way of organizing the chart based on latest activity. There had been one "deleted member" who had been much active in the beginning, but then he/she quit: for months, this member was at the top of the ranking despite not having any activity. Independently on their history of swaps, actively swapping members will appear frequently on the head of the list, and this may be an incentive to do swaps (which is why we are here).