What is {population} of {Maryland} that is {point in time} is {1980-0-0} ?
In 1980, what was Maryland's population?
What was the population of Maryland in 1980?
SELECT ?h WHERE { ?h property:point_in_time ?k . ?h property:population ?h . FILTER ( CONTAINS ( YEAR ( ?k ) , '1980' ) ) . resource:Maryland property:population ?h }
select distinct ?obj  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q1391> .
?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> <1980-0-0>
} 

SELECT ?obj WHERE { wd:Q1391 p:P1082 ?s . ?s ps:P1082 ?obj . ?s pq:P585 ?x filter(contains(YEAR(?x),'1980')) }