Question: in which year did south africa join brics
[{'answer': '2010', 'provenance': [{'wikipedia_id': '32079419', 'title': 'BRICS', 'start_paragraph_id': 1, 'start_character': 244, 'end_paragraph_id': 1, 'end_character': 248, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '32079419', 'title': 'BRICS', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 706, 'bleu_score': 0.7038640368433181, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11622827404061100455}, 'section': 'Section::::Abstract.'}]}]