Question: When did the Free University of Berlin have 4200 employees?
Paraphrase: What year did the Free University of Berlin have 4200 employees?
SPARQL (Wikidata): SELECT ?value WHERE { wd:Q153006 p:P1128 ?s . ?s ps:P1128 ?x filter(contains(?x , '4200.0')) . ?s pq:P585 ?value}