I have daily data like so:

Date Volume
20070103 25
20070103 25
20070103 25
20070103 25
20070103 11
20070103 11
20070104 11
20070104 11
20070103 10
20070203 10
20070203 10

I am trying to find a way to sum the volume by week. Is this possible ?

Thank you in advance.

carl