Hello, I am working on a document and need some expertise.

I have a load of data, which is all sorted by date of occurances. However I need to be able to group these dates into 12 month sections, based upon the dates below but I am not sure how to do this?

What i need is the following:

All occurances between

30/06/2008 and 29/06/2009 - To return a value such as, Period 1
30/06/2009 and 29/06/2010 - Period 2
30/06/2010 and 29/06/2011 - Period 3

Is there a way I can do this using formula in my line by line data?

Thanks for any help and advice anyone can give, it will be greatly appreciated.