Question: when did el salvador switch to the dollar
[{'answer': '2001', 'provenance': [{'wikipedia_id': '1356678', 'title': 'Salvadoran colón', 'start_paragraph_id': 1, 'start_character': 59, 'end_paragraph_id': 1, 'end_character': 63, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1356678', 'title': 'Salvadoran colón', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 303, 'bleu_score': 0.931245760303767, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8982172877464524915}, 'section': 'Section::::Abstract.'}]}]