Sum query help

[Rob]

I have a simple query that calculates a number for each month. I want to add
another field that calculates the cumulative total for each month. For
example, November would = Oct+Nov and December would =Oct+Nov+Dec and so on.
Can this be done in the same query or is coding necessary? Below is the SQL
for the query.
Thanks for the help.
Rob
SELECT [qry York Data -- PTD].Month, Sum([qry York Data -- PTD].[PTD VC
Strategic]) AS [SumOfPTD VC Strategic]
FROM [qry York Data -- PTD]
GROUP BY [qry York Data -- PTD].Month;