График частотности: записка

[{"date": "2011-01-29", "qty": 3}, {"date": "2013-01-19", "qty": 3}, {"date": "2017-04-12", "qty": 11}, {"date": "2018-05-16", "qty": 3}, {"date": "2018-10-29", "qty": 4}, {"date": "2019-04-24", "qty": 3}]