Question: when was the yellow card introduced in football
[{'answer': '1970', 'provenance': [{'wikipedia_id': '5278652', 'title': 'Penalty card', 'start_paragraph_id': 3, 'start_character': 1154, 'end_paragraph_id': 3, 'end_character': 1158, 'bleu_score': 1.0, 'section': 'Section::::History and origin.\n'}]}, {'provenance': [{'wikipedia_id': '5278652', 'title': 'Penalty card', 'start_paragraph_id': 3, 'start_character': 4, 'end_paragraph_id': 3, 'end_character': 1343, 'bleu_score': 0.942893648747763, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1077660731730528293}, 'section': 'Section::::History and origin.\n'}]}]