Question: which continent experiences the highest number of tornadoes per year
[{'answer': 'North America', 'provenance': [{'wikipedia_id': '8293375', 'title': 'Tornado climatology', 'start_paragraph_id': 7, 'start_character': 375, 'end_paragraph_id': 7, 'end_character': 388, 'bleu_score': 1.0, 'section': 'Section::::Geography.\n'}]}, {'provenance': [{'wikipedia_id': '8293375', 'title': 'Tornado climatology', 'start_paragraph_id': 7, 'start_character': 0, 'end_paragraph_id': 7, 'end_character': 1204, 'bleu_score': 0.9768122364125951, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10942384373035865232}, 'section': 'Section::::Geography.\n'}]}]