Question: when did the last episode of charmed air
[{'answer': 'May 21 , 2006', 'provenance': [{'wikipedia_id': '4374934', 'title': 'Forever Charmed', 'start_paragraph_id': 1, 'start_character': 334, 'end_paragraph_id': 1, 'end_character': 349, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '4374934', 'title': 'Forever Charmed', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 665, 'bleu_score': 0.9594798946546471, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7545689295497817950}, 'section': 'Section::::Abstract.'}]}]