Question: when did recreational weed become legal in california
[{'answer': '2016', 'provenance': [{'wikipedia_id': '37646421', 'title': 'Timeline of cannabis laws in the United States', 'start_paragraph_id': 1, 'start_character': 411, 'end_paragraph_id': 1, 'end_character': 415, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]