Question: when did jay z became president of def jam
[{'answer': '2004', 'provenance': [{'wikipedia_id': '2323738', 'title': 'Def Jam Recordings', 'start_paragraph_id': 16, 'start_character': 285, 'end_paragraph_id': 16, 'end_character': 289, 'bleu_score': 1.0, 'section': 'Section::::Company history.:2000s.\n'}]}, {'provenance': [{'wikipedia_id': '2323738', 'title': 'Def Jam Recordings', 'start_paragraph_id': 17, 'start_character': 0, 'end_paragraph_id': 17, 'end_character': 270, 'bleu_score': 0.9062841320510341, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12712542383961333804}, 'section': 'Section::::Company history.:2000s.\n'}]}]