That looks like good information on membership numbers. It also gives some small insight as to whether some of the members consider the AMA to be of benefit to them. There is no accurate way to know year by year how many left the hobby versus those that left the AMA and remained in the hobby. The hobby industry should be a source for some level of information on that matter.

For me it would seem that if the AMA wanted to make a gain on cutting operating expenses that they should try a bi-monthly publication. It would save not only publication and mailing costs it would also cut in half any subsidy afforded advertisers. It would save a lot of paper and ink reprinting the same ads over and over each month.
Also new products are now more likely to be found first on internet advertising rather than a magazine regardless of the publication. Internet will reach world wide to those that are neither a member of AMA or a subscriber to other publications.
Bi-monthly publication would also give the AMA staff more time to address membership issues without increasing the overhead with additional people. The remainder of the money could be put toward some of the often touted but never implemented projects.

If they did not want to try a bi-monthly publication then the advertising rates should equal any other magazine of equivalent distribution. This would at least narrow the gap between loss and profit where the magazine is concerned.