I have a two-dimensional range in Excel like the one in the image.
Along its x-axis are participants (listed in the top of the image) and along the y-axis are activity dates. In the cells are codes for what each participant did on the task. The names are unique, but there may be many activities on the same day, with one row each. Days without activities are not listed. Dates may be entered in any order.
How do I create another range, with the same x-axis (participants), and a y-axis with all days in the year (2024-01-01 through 2024-12-31) showing the activity count per person par day (eg. 1, 2 etc.)
Excel range

I have tried countifs, but there seem to be some fundamental flaw in my understanding of that function.