Question: when was the westgate bridge in melbourne built
[{'answer': '1978', 'provenance': [{'wikipedia_id': '709239', 'title': 'West Gate Bridge', 'start_paragraph_id': 22, 'start_character': 65, 'end_paragraph_id': 22, 'end_character': 69, 'bleu_score': 1.0, 'section': 'Section::::History.:Completion.\n'}]}, {'provenance': [{'wikipedia_id': '709239', 'title': 'West Gate Bridge', 'start_paragraph_id': 22, 'start_character': 0, 'end_paragraph_id': 22, 'end_character': 172, 'bleu_score': 0.9321022168949711, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11803656800032521658}, 'section': 'Section::::History.:Completion.\n'}]}]