OK, so this one's really old but I'm still going to write my answer for future reference.
1. Open the Query Wizard.
2. Select only the fields 'Staff' and 'Number'.
3. Click 'Next' and select 'Summary' from the options provided.
4. Click on 'Summary options', this will open a small window.
5. In this case, click on the 'Sum' radio box and the 'Count records in N9Book' on the bottom right of the window. Click OK.
6. Go through the rest of the wizard as you'd normally do.
7. Create a report using this query.
Et voila!
