I am trying to count how many rooms are occupied based on how many patients are in the clinic at a specific time (down to minutes). I created this Gantt Bar Chart:

I need to count records for each minute mark in the X axis below. for example I want to see that 4 patients/rooms were occupied at 8:00 am, 8:10 am, 8:20 am, then 5 patients/rooms are occupied at 8:30 am, because 2 patients left, 2 patients still receiving some services, and 3 new patients are checked in. another example: 9:00 there were 4 patients, but 9:10 there is a new patient that made the total 5, 9:20 still 5, and so on. When I count it as is now, it only counts 4 at 8:00 am, and 3 at 8:30 am, which means at the appointment start time only.

I am looking forward to some nice thoughts and suggestions..

Thanks in advance

Rawan