query: # % of popes who died in Rome (a rule inferred by AMIE on YAGO, presented by Fabian M. Suchanek in his WikidataCon keynote)
  SELECT (100*SUM(?diedInRome)/COUNT(?pope) AS ?percentDiedInRome) WHERE {
    ?pope wdt:P31 wd:Q5;
          wdt:P39 wd:Q19546.
    OPTIONAL {
      ?pope wdt:P20/(wdt:P276|wdt:P131|wdt:P501)* wd:Q18288160.
      BIND(1 AS ?diedInRome)
    }
  }