Question: what song was number 1 on december 12 1999
[{'answer': 'Smooth', 'provenance': [{'wikipedia_id': '475913', 'title': 'List of Billboard Hot 100 number-one singles of 1999', 'start_paragraph_id': 2, 'start_character': 221, 'end_paragraph_id': 2, 'end_character': 227, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]