1. Drag Port, Sub Port, Site and Building to Rows (in that order)
2. Drag Measure Names to Columns
3. Drag Measure Names to Filters and Select Building Sq Ft and Number of Records
4. Drag Measure Values to Text
5. Right-click the SUM(Building Sq Ft) pill and change the measure to Average
6. From the Menu Bar, select Analysis>Totals>Add All Subtotals
7. From the Menu Bar, select Analysis>Totals>Total All Using>Sum
That should give you the basic layout of the table.