Before the almost complete stop of the EB I-485 processing in the middle of 2002, TSC did go through most cases up until the May 2001 RDs. At that time the processing use to have the following pattern: FP sent 9-10 months after RD, AP normally 2-3 months after FP.
There should be a very small number of unapproved cases left before May 2001. Most likely TSC would be able to move its processing dates to 01 May 2001 very soon.
The months of May, June and July 2001 however are very special. There was a big surge in for both EB and family-based I-485 filings - EB visa dates becomming current and 245i law coming into effect. At the same time INS changed its mail contractor and enterring the filings into the system took 2-3 months.
It is normal for a May 2001 RD to have an August 2001 ND. It is also very difficult to estimate how many cases are in the system for these three months, as scanning May and June reveals a lot of missing SRC # (hence the difficulty of getting more complete picture for these months in the data consolidation project - people are getting blocked very quickly while scanning).
From the scarce data it looks like about 50% of May, June, July RD are approved with this percentage getting smaller as we go to Sep, Oct, Nov, Dec 2001.
The recently reported approvals for May, Aug and Sep 2001 should give us hope that TSC is finally starting to process the remaining cases of 2001.