Question: when did west coast eagles win their last grand final
[{'answer': '2018', 'provenance': [{'wikipedia_id': '295230', 'title': 'West Coast Eagles', 'start_paragraph_id': 2, 'start_character': 459, 'end_paragraph_id': 2, 'end_character': 463, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]