query: #number of person in the Belvedere, by sex
  #defaultView:BubbleChart
  SELECT ?sexColorLabel (COUNT(?person) AS ?count)
  WHERE
  {
    	?person wdt:P3421 [] .   # Artist in Belvedere
  	?person wdt:P21 ?sexColor.
      ?article schema:about ?person .
      ?article schema:isPartOf <https://de.wikipedia.org/>
  	SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
  }
  GROUP BY ?sexColorLabel