I would use a reporting table with the fields Country(ID), Branch(ID), month 1 to 12 and make 12 relations to the main data table using the Country, Branch and month relation.
Then make as many records as needed in that table and fill them with the Country and Branches. Use sorting and finding to make the report needed.
If you add the year in the table you can produce the report by country using the same table.
Hope that helps,
Ruben van den Boogaard
Ruben's option works well. Another option is to build the report using variables or global fields and HTML tables.