Question: when was the 16th amendment added to the constitution
[{'answer': 'February 3 , 1913', 'provenance': [{'wikipedia_id': '31668', 'title': 'Sixteenth Amendment to the United States Constitution', 'start_paragraph_id': 64, 'start_character': 59, 'end_paragraph_id': 64, 'end_character': 80, 'bleu_score': 1.0, 'section': 'Section::::Adoption.\n'}]}]