Administration and Customization
From the Project menu, select Statistics… to access the Project Statistics window.
Note that it may take a few minutes for this window to pop up depending on the number of projects, etc.
This window list all projects and you can also see how many items (rows) each project has.
Since a database and its projects share the same file(s) on the server, there is no data size related to a specific project, but the number of items will of course be a good indication of the space it is using.
You can print a report from this window, or you can rightclick and copy the information and paste to excel. If you would like to check out a given project, you can select that project and open it by clicking Open Project.