EB Statistics confuses me

[vforgc]

According to data published by USCIS on below link, it shows that there are about 60,000 unused visas. The pending I-485 inventory from May shows the pending cases for EB2 is a lot less than 60K. So what's going to happen to all these numbers? Are they going to get used by end of September or going to be a waste?

http://www.uscis.gov/USCIS/Resources/Reports%20and%20Studies/Immigration%20Forms%20Data/Static_files/all-form-types-performance-data-2011-june.pdf

Just want to get insight of people who knows more than I do

Thanks