Question: who was mickey mouse's voice for the first 20 years
[{'answer': 'Walt Disney', 'provenance': [{'wikipedia_id': '20859', 'title': 'Mickey Mouse', 'start_paragraph_id': 1, 'start_character': 71, 'end_paragraph_id': 1, 'end_character': 82, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '20859', 'title': 'Mickey Mouse', 'start_paragraph_id': 61, 'start_character': 0, 'end_paragraph_id': 61, 'end_character': 1110, 'bleu_score': 0.515889974325348, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9480288820431255701}, 'section': 'Section::::Portrayal.:Voice actors.\n'}]}]