Question: when was pin code system introduced in india
[{'answer': '15 August 1972', 'provenance': [{'wikipedia_id': '476964', 'title': 'Postal Index Number', 'start_paragraph_id': 3, 'start_character': 33, 'end_paragraph_id': 3, 'end_character': 47, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '476964', 'title': 'Postal Index Number', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 334, 'bleu_score': 0.9185328633513561, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14265950472306990111}, 'section': 'Section::::History.\n'}]}]