SELECT  (COUNT(*) as ?frequency)
WHERE 
{
?s owl:sameAs ?idRef
  FILTER (CONTAINS(STR(?idRef), 'idref')) 
}

SELECT ?class ?classLabel ?frequency
WHERE {
          {
          SELECT ?class (COUNT(*) as ?frequency)
            WHERE 
            {
             ?s owl:sameAs ?idRef;
                  a ?class.
              FILTER (CONTAINS(STR(?idRef), 'idref')) 
            }
            GROUP BY ?class ?classLabel
          }
  ?class rdfs:label ?classLabel.  
}

ORDER BY DESC(?frequency)