A rate can be constituted-of-or-filled-with some square miles.
Some square feet can be constituted-of-or-filled-with (manufacturing space).
An average can be constituted-of-or-filled-with some square feet.
Some square kilometres can be constituted-of-or-filled-with forest.
Some square meters can be constituted-of-or-filled-with area.
A (floor space) can be constituted-of-or-filled-with some square metres.