Question: when did table tennis change from 21 to 11
[{'answer': 'September 2001', 'provenance': [{'wikipedia_id': '30589', 'title': 'Table tennis', 'start_paragraph_id': 11, 'start_character': 645, 'end_paragraph_id': 11, 'end_character': 659, 'bleu_score': 1.0, 'section': 'Section::::History.:Rule changes.\n'}]}, {'provenance': [{'wikipedia_id': '30589', 'title': 'Table tennis', 'start_paragraph_id': 11, 'start_character': 0, 'end_paragraph_id': 11, 'end_character': 929, 'bleu_score': 0.702880318724128, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13410136352633568092}, 'section': 'Section::::History.:Rule changes.\n'}]}]