what is the {end time} for {Willis Tower} has {owned by} as {Willis Group} ?
When did the Willis Group sell Willis Tower?
SELECT ?value WHERE { wd:Q29294 p:P127 ?s . ?s ps:P127 wd:Q919120 . ?s pq:P582 ?value}
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q29294> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P127> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q919120> .
?statement <http://www.wikidata.org/entity/P582> ?value. 
} 

What was the year when willis tower sold by willis group?