Question: when did conan stop writing for the simpsons
[{'answer': '1993', 'provenance': [{'wikipedia_id': '4221870', 'title': "Conan O'Brien", 'start_paragraph_id': 2, 'start_character': 518, 'end_paragraph_id': 2, 'end_character': 522, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '4221870', 'title': "Conan O'Brien", 'start_paragraph_id': 14, 'start_character': 0, 'end_paragraph_id': 14, 'end_character': 736, 'bleu_score': 0.9846731957240711, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1085751439948049953}, 'section': 'Section::::Career.:"The Simpsons" (1991–1993).\n'}]}]