Question: when did germany start using the metric system
[{'answer': 'January 1 , 1872 ,'}, {'provenance': [{'wikipedia_id': '2620499', 'title': 'Obsolete German units of measurement', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 99, 'bleu_score': 0.510863694273149, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17415933420739624749}, 'section': 'Section::::Abstract.'}]}]