Question: how many un secretary generals have there been
[{'answer': '9', 'provenance': [{'wikipedia_id': '162415', 'title': 'Secretary-General of the United Nations', 'start_paragraph_id': 1, 'start_character': 376, 'end_paragraph_id': 1, 'end_character': 377, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]