Question: when was led zeppelin's first album released
[{'answer': '12 January 1969', 'provenance': [{'wikipedia_id': '44640', 'title': 'Led Zeppelin (album)', 'start_paragraph_id': 1, 'start_character': 86, 'end_paragraph_id': 1, 'end_character': 101, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]