Question: when did the concept of sustainable development come into existence
[{'answer': '1987', 'provenance': [{'wikipedia_id': '29501', 'title': 'Sustainable development', 'start_paragraph_id': 2, 'start_character': 79, 'end_paragraph_id': 2, 'end_character': 83, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '29501', 'title': 'Sustainable development', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 1175, 'bleu_score': 0.927778540361433, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2376272891135808416}, 'section': 'Section::::Abstract.'}]}]