Report on how much EV will expire on a certain date?

Hi,

We started using EV 7 in 2007 and upgraded to version 9 in 2012.  We set retention to 7 years.  So sometime this year it is going to delete some expired items.  My question is, is there a way to find out how much data will be expired or deleted on a given date.  Can we predict or report on how much will be expired in the year 2014?   Also, I read somewhere that after doing an upgrade, all historical trend is gone. Is it true?  When I ran an "Items Archival Rate" report for 2007, it doesn't look right at all.

Thanks.

Gogeta