1. Add subtotals to the List.
2. In the Subtotal levels, click level 2.
3. Select a cell in the List, and press Ctrl+Shift+* or press Ctrl+A.
4. Press Alt+; to select visible cells only.
Or
Select Home -> Find & Select (in Editing tab) -> Go To Special -> Visible cells only.
Or
Press F5 -> Special -> Visible cells only.
5. Copy and paste the subtotals summary to a different sheet.