График частотности: разобраться

[{"date": "2013-03-25", "qty": 6}, {"date": "2013-08-22", "qty": 3}, {"date": "2013-10-14", "qty": 3}, {"date": "2013-11-15", "qty": 3}, {"date": "2013-11-16", "qty": 3}, {"date": "2013-11-17", "qty": 6}, {"date": "2013-11-26", "qty": 3}, {"date": "2014-03-08", "qty": 3}, {"date": "2014-03-09", "qty": 3}, {"date": "2014-03-10", "qty": 3}, {"date": "2014-03-11", "qty": 3}, {"date": "2015-04-07", "qty": 12}, {"date": "2015-04-28", "qty": 4}, {"date": "2015-09-25", "qty": 12}, {"date": "2015-11-19", "qty": 3}, {"date": "2015-11-20", "qty": 4}, {"date": "2016-02-22", "qty": 3}, {"date": "2016-07-17", "qty": 3}, {"date": "2017-07-09", "qty": 3}, {"date": "2017-07-10", "qty": 4}, {"date": "2018-01-03", "qty": 3}, {"date": "2020-06-25", "qty": 3}, {"date": "2020-10-05", "qty": 3}, {"date": "2021-12-04", "qty": 7}, {"date": "2022-02-16", "qty": 3}, {"date": "2022-08-22", "qty": 3}, {"date": "2022-08-24", "qty": 3}, {"date": "2023-01-13", "qty": 3}, {"date": "2023-01-14", "qty": 3}, {"date": "2023-01-15", "qty": 3}]