Question: when did the microwave become a common household item
[{'answer': 'the late 1970s', 'provenance': [{'wikipedia_id': '58017', 'title': 'Microwave oven', 'start_paragraph_id': 2, 'start_character': 794, 'end_paragraph_id': 2, 'end_character': 808, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '58017', 'title': 'Microwave oven', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 993, 'bleu_score': 0.937484515510385, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8431079886419650303}, 'section': 'Section::::Abstract.'}]}]