Question: who has the most followers on youtube 2018
[{'answer': 'PewDiePie', 'provenance': [{'wikipedia_id': '40199886', 'title': 'List of most-subscribed YouTube channels', 'start_paragraph_id': 2, 'start_character': 202, 'end_paragraph_id': 2, 'end_character': 211, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '40199886', 'title': 'List of most-subscribed YouTube channels', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 419, 'bleu_score': 0.641107104909314, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12427366582502751204}, 'section': 'Section::::Abstract.'}]}]