I have this query:

SELECT q.GroupId, 
       (SumOfcert_complete/CountOfcert_complete)*100 AS Percent_Certified, 
       Groups.GroupName
    FROM qryGroupCert_base AS q 
    INNER JOIN Groups ON q.GroupId=Groups.GroupId

It results in

GroupId	percent_certified	GroupName
286	           58            Group A
287	           58 	         Group B
288	          100	         Group C
289	          100	         Group D

I would like to add a summary row that shows the total percentage, so that I would end up with

GroupId	percent_certified	GroupName
286	           58            Group A
287	           58 	         Group B
288	          100	         Group C
289	          100	         Group D
0                 315            All

So far I tried this:

SELECT q.GroupId, 
      (SumOfcert_complete/CountOfcert_complete)*100 AS percent_certified,
      (Sum(SumOfcert_complete/CountOfcert_complete)*100)) / 4 AS Total,
      Groups.GroupName
FROM qryGroupCert_base AS q INNER JOIN Groups ON q.GroupId=Groups.GroupId;

but it's not quite right. What's wrong here?