The last I checked for every registered member there were a large # (8 IIRC)of viewers who don't register but just read. Also there are quite a few mag. subscribers who don't do the Forum thing. It is not a direct comparison of people.
One thing is clear though. If you read this Forum you are benefiting from the mag. Either through sharing in the posters discussion of the substance (getting questions answered) , having a place to read/share or by the mag. making the Forum possible. You would be surprised by the number of people who are long time readers/posters with only a few posts. So like Dudley said try to do your part in sharing the load.