query: SELECT ?instance ?instanceLabel ?ct 
  {
      {
          SELECT ?instance (COUNT(DISTINCT ?item) as ?ct)
  		{
  			?item wdt:P345 ?imdb  .
             	FILTER (SUBSTR(?imdb,1,2)='tt') .
            	?item wdt:P31 ?instance .
          }	
  		GROUP BY ?instance
  		# ORDER BY DESC(?ct)
          # LIMIT 500
      }
      SERVICE wikibase:label { bd:serviceParam wikibase:language "en" }
  }
  ORDER BY DESC(?ct)