Question: when did modern campaign finance regulation in the united states begin
[{'answer': '1971', 'provenance': [{'wikipedia_id': '40557', 'title': 'Campaign finance reform in the United States', 'start_paragraph_id': 2, 'start_character': 217, 'end_paragraph_id': 2, 'end_character': 221, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '40557', 'title': 'Campaign finance reform in the United States', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 1175, 'bleu_score': 0.988472140978305, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4888981227863660091}, 'section': 'Section::::Abstract.'}]}]