Question: when did day light savings time start in the united states
[{'answer': '1967', 'provenance': [{'wikipedia_id': '16190896', 'title': 'Daylight saving time in the United States', 'start_paragraph_id': 10, 'start_character': 188, 'end_paragraph_id': 10, 'end_character': 192, 'bleu_score': 1.0, 'section': 'Section::::History of DST in the United States.:1966–1972: Federal standard established.\n'}]}, {'provenance': [{'wikipedia_id': '16190896', 'title': 'Daylight saving time in the United States', 'start_paragraph_id': 10, 'start_character': 0, 'end_paragraph_id': 10, 'end_character': 1174, 'bleu_score': 0.9343874031879691, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6474572850603140798}, 'section': 'Section::::History of DST in the United States.:1966–1972: Federal standard established.\n'}]}]