Question: What is the founding year of the brewery that produces Pilsner Urquell?
SPARQL query:
PREFIX prop: <http://dbpedia.org/property/>
PREFIX res: <http://dbpedia.org/resource/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?num WHERE
{
	res:Pilsner_Urquell prop:brewery ?uri .
	?uri prop:foundation ?num .
	OPTIONAL { ?uri rdfs:label ?string. FILTER (lang(?string) = 'en') }
}