query: SELECT ?parent ?parentLabel (COUNT(?constituency) AS ?constituencies) WHERE {   
    ?person p:P39 ?position_statement .
    ?position_statement ps:P39 wd:Q17592486 .
    ?position_statement pq:P768 ?constituency .
    ?constituency wdt:P31 ?parent .
    SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . }
  }
  GROUP BY ?parent ?parentLabel
  