You'll need to use groups and totals... but without a sample of your data it's hard to know exactly what the query would look like... can you post up a sample?
This is an example of a 'similar' query I have in one of my databases... it's based on a single table - the table contains a list of Training course Attendees, including the name of the branch they work for, and a simple Yes/No field (Leftcompany) to show who still works there....
The following query gives me a summary of how many staff on the database work for RMS, how many are 'past' (ie, have left), and then what percentage of the total number that is
SELECT Count(Attendees.[Branch]) AS RMS, Sum(-([leftcompany])) AS Past, Sum(-([leftcompany]))/Count([Branch]) AS [Percent]
In the datasheet view, this shows RMS as 88, Past as 25, and Percent as 28.41%
Does that help you at all?
Last edited by CazB; 08-12-2013 at 04:45 AM.