prefix bsbm: <http://www4.wiwiss.fu-berlin.de/bizer/bsbm/v01/vocabulary/>
prefix rev: <http://purl.org/stuff/rev#>

Select ?productType ?reviewCount
{
 { Select ?productType (count(?review) As ?reviewCount)
  {
   ?productType a bsbm:ProductType .
   ?product a ?productType .
   ?product bsbm:producer ?producer .
   ?producer bsbm:country %Country1% .
   ?review bsbm:reviewFor ?product .
   ?review rev:reviewer ?reviewer .
   ?reviewer bsbm:country %Country2% .
  }
  Group By ?productType
 }
}
Order By desc(?reviewCount) ?productType
Limit 10