Question: when did the a 10 warthog enter service
[{'answer': '1976', 'provenance': [{'wikipedia_id': '12502446', 'title': 'Fairchild Republic A-10 Thunderbolt II', 'start_paragraph_id': 1, 'start_character': 592, 'end_paragraph_id': 1, 'end_character': 596, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '12502446', 'title': 'Fairchild Republic A-10 Thunderbolt II', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 889, 'bleu_score': 0.893146922775203, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 931236442887088583}, 'section': 'Section::::Abstract.'}]}]