First and Second Succession War books provide factory counts e.g. Galax 0 (2) or Hesperus II 7 (1). Interstellar Operations doesn't use that e.g. Galax 1.
What's in the brackets, shipyards? Does that factor into creating aerospace formations, which doesn't seem to distinguish between fighter, DropShip, JumpShip, or WarShip production?
