Question: when was the additional child tax credit introduced
[{'answer': 'Taxpayer Relief Act of 1997', 'provenance': [{'wikipedia_id': '1515088', 'title': 'Child tax credit', 'start_paragraph_id': 13, 'start_character': 181, 'end_paragraph_id': 13, 'end_character': 208, 'bleu_score': 1.0, 'section': 'Section::::United States.:Changes under the TCJA of 2017.\n'}]}, {'provenance': [{'wikipedia_id': '1515088', 'title': 'Child tax credit', 'start_paragraph_id': 13, 'start_character': 87, 'end_paragraph_id': 13, 'end_character': 793, 'bleu_score': 0.837554112158673, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5767027939531391179}, 'section': 'Section::::United States.:Changes under the TCJA of 2017.\n'}]}]