Formula that calculates # of lead in past week

Hi,

We have a numeric (summary) field that calculates our # of leads (all time). This is a lookup field. 

So, if we have 30 leads all time from Facebook, I can easily see that in a report by displaying the "# of leads" field. 

However, I would like to also show in the report how many leads did we get last week? How many leads in the last 2 weeks?

Is there a way to do this using Report Formulas, or by creating a field with a formula? Other suggestions?

Here's a couple of screenshots to help you see what I am seeing...

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Thanks!

Matt

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Mathew Crist
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