Question: when were nutrition labels introduced in the us
[{'answer': '1990', 'provenance': [{'wikipedia_id': '3426093', 'title': 'Nutrition facts label', 'start_paragraph_id': 32, 'start_character': 74, 'end_paragraph_id': 32, 'end_character': 78, 'bleu_score': 1.0, 'section': 'Section::::United States.:Description.\n'}]}, {'provenance': [{'wikipedia_id': '3426093', 'title': 'Nutrition facts label', 'start_paragraph_id': 32, 'start_character': 0, 'end_paragraph_id': 32, 'end_character': 765, 'bleu_score': 0.983672097934538, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10952116501481333844}, 'section': 'Section::::United States.:Description.\n'}]}]