What is {population} of {Rwanda} that is {point in time} is {1989-0-0} ?
which  Rwanda  population  in  the year 1989?
What was the population of Rwanda in 1989?
SELECT ?p WHERE { FILTER ( CONTAINS ( YEAR ( ?j ) , '1989' ) ) . resource:Rwanda property:population ?m . ?m property:population ?p . ?m property:point_in_time ?j }
select distinct ?obj  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q1037> .
?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> <1989-0-0>
} 

SELECT ?obj WHERE { wd:Q1037 p:P1082 ?s . ?s ps:P1082 ?obj . ?s pq:P585 ?x filter(contains(YEAR(?x),'1989')) }