Question: how many rookies in the 2018 indy 500
[{'answer': 'Four', 'provenance': [{'wikipedia_id': '54168860', 'title': '2018 Indianapolis 500', 'start_paragraph_id': 27, 'start_character': 0, 'end_paragraph_id': 27, 'end_character': 4, 'bleu_score': 1.0, 'section': 'Section::::Schedule.\n'}]}, {'provenance': [{'wikipedia_id': '54168860', 'title': '2018 Indianapolis 500', 'start_paragraph_id': 38, 'start_character': 0, 'end_paragraph_id': 38, 'end_character': 1876, 'bleu_score': 0.9014637038063291, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2407669951016835764}, 'section': 'Section::::Testing and rookie orientation.:Rookie Orientation Program / Refresher tests — Tuesday May 1.\n'}]}]