We should also bear in mind that the sponsorship option has been taken up by very few people, we have maybe one citizen in this category currently and I doubt we have had more than a handfull overall. The "problem" it was intended to solve - a low-cost route when low-priced land is not available - has not really materialised. We often seem to imagine that there are hordes of eager prospective citizens just dying to join us. The fact would seem to be that there aren't, and that those who do want to join us want to own land - which is why I hope we will expand soon.
We should, perhaps, be thankful that few people have taken up this option. If all (or many) of our current citizens were to abandon their land and downsize to become sponsor citizens, we wouldn't be able to cover our monthly tier from the income (assuming that the abandoned land wasn't quickly snapped up).