query: SELECT ?qual ?qualLabel ?count 
  WHERE {
    {
      SELECT ?qual (COUNT(DISTINCT ?person) AS ?count) WHERE {
        ?person p:P39 [ ps:P39 [ wdt:P279* wd:Q21328577 ]; ?pq_qual ?pq_obj ] .
        ?qual wikibase:qualifier ?pq_qual .
      }
      GROUP BY ?qual ?qualLabel
    }
    SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . }
  }
  ORDER BY DESC (?count)
  