query: #defaultView:BubbleChart
  SELECT ?rgb ?colorLabel (COUNT(?compound) AS ?count)
  WHERE
  {
    ?compound wdt:P31 wd:Q11173;
              wdt:P462 ?color.
    OPTIONAL { ?color wdt:P465 ?rgb. }
    BIND(IF(BOUND(?rgb),?rgb,"CCCCCC") AS ?rgb).
    SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
  }
  GROUP BY ?rgb ?colorLabel