Question: when did the first usb flash drive appear on the retail market
[{'answer': 'early 2000', 'provenance': [{'wikipedia_id': '400414', 'title': 'USB flash drive', 'start_paragraph_id': 6, 'start_character': 477, 'end_paragraph_id': 6, 'end_character': 487, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '400414', 'title': 'USB flash drive', 'start_paragraph_id': 6, 'start_character': 234, 'end_paragraph_id': 6, 'end_character': 1160, 'bleu_score': 0.856947386010787, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6548748352228864654}, 'section': 'Section::::History.\n'}]}]