Question: where do tornadoes happen most in the world
[{'answer': 'United States', 'provenance': [{'wikipedia_id': '8293375', 'title': 'Tornado climatology', 'start_paragraph_id': 1, 'start_character': 184, 'end_paragraph_id': 1, 'end_character': 197, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '8293375', 'title': 'Tornado climatology', 'start_paragraph_id': 1, 'start_character': 10, 'end_paragraph_id': 1, 'end_character': 794, 'bleu_score': 0.8184285340100981, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 18376361122820930553}, 'section': 'Section::::Abstract.'}]}]