Question: when was the wcag 2.0 guidelines rolled out
[{'answer': 'December 2008', 'provenance': [{'wikipedia_id': '5291317', 'title': 'Web Content Accessibility Guidelines', 'start_paragraph_id': 1, 'start_character': 484, 'end_paragraph_id': 1, 'end_character': 497, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '5291317', 'title': 'Web Content Accessibility Guidelines', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 611, 'bleu_score': 0.7465874889092261, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12180340097411314571}, 'section': 'Section::::Abstract.'}]}]