I'm stumped on this one.

I have a report that shows production calculations for a user-selected
period divided up into weeks.  Currently, I just use
format([MyField],"ww") to get the calendar week for the purposes of
grouping the data.  However, my users would rather that I display the
number of the week in the period they've selected.  If, for instance,
they select 2/1/2006 to 2/28/2006, they want to see "Week 1," "Week 2,"
"Week 3," etc. rather than the actual calendar weeks of 5, 6, 7, and 8.
Hope that makes sense.

Any ideas how I'd go about doing this?  Thanks in advance for any
suggestions.

-Josh Nikle