There currently are no seated NASFiCs, because all future seated Worldcons are in North America.
A NASFiC is held in North America in any year where the Worldcon is outside of North America.
The NASFiC.org web site does not operate individual NASFiCs. Each NASFiC is operated by its individual operating committee, not by a central organization. The World Science Fiction Society does not operate NASFiC or Worldcon. It is only the sanctioning entity, and does not operate conventions. Contact each individual convention with questions about that convention.