Question: how many teams are there in the afl
[{'answer': '18', 'provenance': [{'wikipedia_id': '4732785', 'title': 'Australian Football League', 'start_paragraph_id': 1, 'start_character': 420, 'end_paragraph_id': 1, 'end_character': 422, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]