Question: when did the first walmart open in maryland
[{'answer': '1991', 'provenance': [{'wikipedia_id': '6119571', 'title': 'History of Walmart', 'start_paragraph_id': 13, 'start_character': 178, 'end_paragraph_id': 13, 'end_character': 182, 'bleu_score': 1.0, 'section': 'Section::::1980s and 1990s.\n'}]}, {'provenance': [{'wikipedia_id': '6119571', 'title': 'History of Walmart', 'start_paragraph_id': 17, 'start_character': 0, 'end_paragraph_id': 17, 'end_character': 377, 'bleu_score': 0.9657992495762461, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14029741398930983080}, 'section': 'Section::::1980s and 1990s.\n'}]}]