Calculating visits in a month as a percentage?

Calculating visits in a month as a percentage?

First, thanks for your time. I'm sure this is possible, I just can't figure out how to configure it.

I have a table that lists the visitors to our business and what day they come in. I'd like to calculate how many days they visit as a percentage of how many days they possibly could in that month (in our situation, any day Monday to Friday). I've created an aggregate formula in the base table to calculate how many possible days visitors could come in, but I can't figure out how to format any pivot view or summary view to display it as a percentage.

I would appreciate any help. Thank you so much!