Question: how many tournament grass courts does wimbledon have
[{'answer': '18', 'provenance': [{'wikipedia_id': '1598742', 'title': 'All England Lawn Tennis and Croquet Club', 'start_paragraph_id': 5, 'start_character': 79, 'end_paragraph_id': 5, 'end_character': 81, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '1598742', 'title': 'All England Lawn Tennis and Croquet Club', 'start_paragraph_id': 13, 'start_character': 0, 'end_paragraph_id': 13, 'end_character': 564, 'bleu_score': 0.9792717993254391, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2208910839893906285}, 'section': 'Section::::Facilities.\n'}]}]