Question: when did google start as a search engine
[{'answer': 'September 4 , 1998', 'provenance': [{'wikipedia_id': '4338696', 'title': 'History of Google', 'start_paragraph_id': 14, 'start_character': 231, 'end_paragraph_id': 14, 'end_character': 251, 'bleu_score': 1.0, 'section': 'Section::::History.:Late 1990s.\n'}]}, {'provenance': [{'wikipedia_id': '4338696', 'title': 'History of Google', 'start_paragraph_id': 14, 'start_character': 0, 'end_paragraph_id': 14, 'end_character': 314, 'bleu_score': 0.874678895739835, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15431513573029576886}, 'section': 'Section::::History.:Late 1990s.\n'}]}]