Question: when is the last time california executed a prisoner
[{'answer': '2006', 'provenance': [{'wikipedia_id': '413896', 'title': 'Capital punishment in California', 'start_paragraph_id': 2, 'start_character': 504, 'end_paragraph_id': 2, 'end_character': 508, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '413896', 'title': 'Capital punishment in California', 'start_paragraph_id': 2, 'start_character': 170, 'end_paragraph_id': 2, 'end_character': 485, 'bleu_score': 0.5296862814904101, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8807205887882941523}, 'section': 'Section::::Abstract.'}]}]