query: SELECT ?item 
  (COUNT(?painting) AS ?paintingcount) (COUNT(?image) AS ?imagecount) 
  ((COUNT(?painting)-COUNT(?image)) AS ?missingimagecount) (ROUND(COUNT(?image)/COUNT(?painting)*100) AS ?percentage) WHERE {
    ?painting wdt:P31 wd:Q3305213 ;
          wdt:P195 ?item ;
          wdt:P6216 wd:Q19652 .
    OPTIONAL { ?painting wdt:P18 ?image }
    } GROUP BY ?item
  ORDER BY DESC (?imagecount)
  LIMIT 200