Flightaware.com

For example, Wednesday's JFK departure arrived 9:31a, and onward flight left 9:59a. I consider this to be a misconnect.

Scheduled arrive is 8:25a, departure 9:50a. For purposes of my analysis, I consider any connection inside of 60 minutes to be a failure. By this measure, only a single connection could have occured in June. If I take a more liberal approach and consider any connection inside of 45 minutes to be a failure (so, 9:05a or later arrival time), then 13 of 21 days misconnected. Keep in mind we are traveling with children, so one should not necessarily apply their own, "flying solo and can run quickly" criteria when determining whether a sub-60 minute connection is reasonably considered a failure.