Question: when did london's population reach 1 million
[{'answer': '1800', 'provenance': [{'wikipedia_id': '14020', 'title': 'History of London', 'start_paragraph_id': 79, 'start_character': 155, 'end_paragraph_id': 79, 'end_character': 159, 'bleu_score': 1.0, 'section': 'Section::::Modern history.:19th century.\n'}]}, {'provenance': [{'wikipedia_id': '14020', 'title': 'History of London', 'start_paragraph_id': 79, 'start_character': 0, 'end_paragraph_id': 79, 'end_character': 415, 'bleu_score': 0.9712154609069981, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15719165069930510159}, 'section': 'Section::::Modern history.:19th century.\n'}]}]