Question: in 2011 what was the dominant source of energy in the world
[{'answer': 'coal', 'provenance': [{'wikipedia_id': '9058630', 'title': 'World energy consumption', 'start_paragraph_id': 3, 'start_character': 407, 'end_paragraph_id': 3, 'end_character': 411, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]