Requesting Help on a metric formula

I am working with a sample diabetic patient screening data and here is the metric -

Ex1. A = Total number of patients screened by the team.
B = Total no of working days. (Target screening defined per day = 150); So for calculating Average number of screening per day i am using Avg = A/B.

Example 2. For given number of days (say 10 days) screening has not performed or minimal screening performed at day 3 and day 4. If i have to capture/identify that specific day causing the downtime .......what should be my metric formula?