query: SELECT ?item (COUNT(DISTINCT ?artwork) AS ?count) WHERE {
     ?artwork wdt:P31/wdt:P279* wd:Q838948 . 
    ?artwork p:P528 ?catalogstatement .
    ?catalogstatement ps:P528 ?catalogid . 
    ?catalogstatement pq:P972 ?item .
    } GROUP BY ?item
  ORDER BY DESC(?count)