I have the following schema in MySQL (read only permissions database)
As you can see there are only 5 country codes:
GB, USA, GR, ES, DE
Ok, so in lieu of a functional SQLFiddle I will make a few assumptions. The country code exists in the same table as the grouped data.
If that is the case, why not use:
select DT1.CountryCode, count(DT2.ValueForCounting) as ReturnedCount from ( select distinct CountryCode from DataTable ) DT1 left join DataTable DT2 on DT1.CountryCode = DT2.CountryCode and DT2.QueryConditions = 'Stuff' -- Use the join condition instead of a where clause for anything to do with DT2