What is {population} of {Mashhad} that is {point in time} is {1991-9-11} ?
On September 11, 1991, how many people populated Mashhad?
What was the population of Mashhad on September 11th, 1991?
SELECT ?t WHERE { FILTER ( CONTAINS ( YEAR ( ?a ) , '1991' ) ) . resource:Mashhad property:population ?q . ?q property:point_in_time ?a . ?q property:population ?t }
select distinct ?obj  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q121157> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P1082> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
?statement <http://www.wikidata.org/entity/P585> <1991-9-11>
} 

SELECT ?obj WHERE { wd:Q121157 p:P1082 ?s . ?s ps:P1082 ?obj . ?s pq:P585 ?x filter(contains(YEAR(?x),'1991')) }