Question: how much did chelsea sell de bruyne to wolfsburg
[{'answer': '£ 18 million', 'provenance': [{'wikipedia_id': '19570009', 'title': 'Kevin De Bruyne', 'start_paragraph_id': 18, 'start_character': 60, 'end_paragraph_id': 18, 'end_character': 73, 'bleu_score': 1.0, 'section': 'Section::::Club career.:Wolfsburg.:2013–14 season.\n'}]}, {'provenance': [{'wikipedia_id': '19570009', 'title': 'Kevin De Bruyne', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 397, 'bleu_score': 0.9277431284700741, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13370620409585030640}, 'section': 'Section::::Abstract.'}]}]