Question: when was the rio+20 summit in rio de janeiro held
[{'answer': '2012', 'provenance': [{'wikipedia_id': '324783', 'title': 'Earth Summit', 'start_paragraph_id': 3, 'start_character': 3, 'end_paragraph_id': 3, 'end_character': 7, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '324783', 'title': 'Earth Summit', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 179, 'bleu_score': 0.83851300471302, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 545725811216512865}, 'section': 'Section::::Abstract.'}]}]