График частотности: четвертьфинал

[{"date": "2011-02-28", "qty": 4}, {"date": "2011-03-01", "qty": 3}, {"date": "2011-03-17", "qty": 3}, {"date": "2011-06-27", "qty": 4}, {"date": "2012-01-23", "qty": 3}, {"date": "2012-03-07", "qty": 3}, {"date": "2012-03-08", "qty": 7}, {"date": "2012-06-04", "qty": 3}, {"date": "2012-06-17", "qty": 3}, {"date": "2012-06-18", "qty": 3}, {"date": "2012-10-18", "qty": 3}, {"date": "2012-10-31", "qty": 3}, {"date": "2013-09-04", "qty": 3}, {"date": "2014-02-16", "qty": 3}, {"date": "2014-07-01", "qty": 5}, {"date": "2014-10-30", "qty": 3}, {"date": "2016-03-01", "qty": 3}, {"date": "2017-09-11", "qty": 5}, {"date": "2017-09-12", "qty": 5}, {"date": "2017-10-25", "qty": 3}, {"date": "2018-02-17", "qty": 8}, {"date": "2018-07-01", "qty": 9}, {"date": "2018-07-02", "qty": 6}, {"date": "2018-07-06", "qty": 3}, {"date": "2018-07-07", "qty": 3}]