Question: when was the first hdb flat built in singapore
[{'answer': '1960', 'provenance': [{'wikipedia_id': '8609713', 'title': 'Public housing in Singapore', 'start_paragraph_id': 10, 'start_character': 12, 'end_paragraph_id': 10, 'end_character': 16, 'bleu_score': 1.0, 'section': 'Section::::History.:HDB post independence.\n'}]}, {'provenance': [{'wikipedia_id': '8609713', 'title': 'Public housing in Singapore', 'start_paragraph_id': 13, 'start_character': 0, 'end_paragraph_id': 13, 'end_character': 727, 'bleu_score': 0.9577362712813341, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1988603096215503767}, 'section': 'Section::::History.:HDB post independence.\n'}]}]