Question: when did they stop using asbestos in popcorn ceilings
[{'answer': '1978'}, {'provenance': [{'wikipedia_id': '9728495', 'title': 'Popcorn ceiling', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 690, 'bleu_score': 0.95005935086738, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2112870514763040325}, 'section': 'Section::::Abstract.'}]}]