query: #defaultView:AreaChart
  SELECT ?st ?ct {
    {
     BIND (0 AS ?ct)
     BIND (-0.0001 AS ?st)
    }
    UNION {
      SELECT ?st (COUNT(*) as ?ct)
      {
        ?item wdt:P2092 ?value ; wikibase:sitelinks ?st
      }
      GROUP BY ?st
      ORDER BY ?st
    }
  }