Question: when did the nba start and how many teams were there
[{'answer': 'August 3 , 1949', 'provenance': [{'wikipedia_id': '22093', 'title': 'National Basketball Association', 'start_paragraph_id': 7, 'start_character': 3, 'end_paragraph_id': 7, 'end_character': 18, 'bleu_score': 1.0, 'section': 'Section::::History.:Creation and BAA–NBL merger (1946–1956).\n'}]}, {'answer': 'seventeen', 'provenance': [{'wikipedia_id': '22093', 'title': 'National Basketball Association', 'start_paragraph_id': 8, 'start_character': 19, 'end_paragraph_id': 8, 'end_character': 28, 'bleu_score': 1.0, 'section': 'Section::::History.:Creation and BAA–NBL merger (1946–1956).\n'}]}, {'provenance': [{'wikipedia_id': '22093', 'title': 'National Basketball Association', 'start_paragraph_id': 8, 'start_character': 0, 'end_paragraph_id': 8, 'end_character': 833, 'bleu_score': 0.6574083540801681, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5462566775582878440}, 'section': 'Section::::History.:Creation and BAA–NBL merger (1946–1956).\n'}]}]