query: #the number of songs named after days of the week by day
  #defaultView:BarChart
  SELECT ?day ?dayLabel (COUNT(DISTINCT ?item) AS ?songCount) WHERE {
    ?day wdt:P31 wd:Q41825.
    ?item wdt:P31/wdt:P279* wd:Q7366; wdt:P138 ?day.
    SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
  }
  GROUP BY ?day ?dayLabel