What is {population} of {Catania} that is {point in time} is {2017-1-1} ?
What was Catania's population at the start of 2017?
What was the population of Catania in 2017-1-1?
SELECT ?e WHERE { ?h property:population ?e . resource:Catania property:population ?h . ?h property:point_in_time ?l . FILTER ( CONTAINS ( YEAR ( ?l ) , '2017' ) ) }
select distinct ?obj  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q1903> .
?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> <2017-1-1>
} 

SELECT ?obj WHERE { wd:Q1903 p:P1082 ?s . ?s ps:P1082 ?obj . ?s pq:P585 ?x filter(contains(YEAR(?x),'2017')) }