Counting the number of duplicates per date

Hello everyone!

I have a large data set that I am working with that has two relevant columns, a date and an id key. What I am trying to figure out is the best way to count the number of duplicates per individual date.

For example, if the id key ‘12345’ appeared three times on 1 January, ‘3456’ appeared twice on 1 January, and ‘12345’ appeared twice on 2 January I woud be looking for something like the following.

Date Duplicates

1 Jan 5

2 Jan 2

Any help appreciated!