Question: when was the last time china held the olympics
[{'answer': '2008', 'provenance': [{'wikipedia_id': '8341323', 'title': 'China at the Olympics', 'start_paragraph_id': 21, 'start_character': 251, 'end_paragraph_id': 21, 'end_character': 255, 'bleu_score': 1.0, 'section': 'Section::::History.:Summer Games.:Sports summary.\n'}]}]