Trying to Create a Spreadsheet that shows # of individuals attending on a specific day

I'm trying to create a spreadsheet in which we're keeping track of individuals attending on specific days of the week. Example: How many individuals attended on Mondays in the month of January and then for the rest of the months of the year. We're looking to see a trend of which days have more attendance. I thought I had it be having the months of the year as my first column and then columns with #'s 1-31 across the top split with the day of the week drop-down option. However, I don't think this will allow me to grab all of the Mondays in the month. Anybody have any suggestions since I'm hitting a mental block and I'm not familiar with all the functionality of Excel.

Thank you so much for your help! Happy Holidays!