The portfolio is way to small to calculate like that, after a year the best names would have sold thru, and the weaker ones tend to just keep on carrying thru with renewals.
If it was 5,000 there might be better potential, and a portfolio of 600 it can easily be scanned, and ranked on a 1 by 1 basis. Especially if it focuses on a single trend which could be current at this very moment, but not current a year from now.
Post your top 100 names in the thread if you want to see what it is really worth, and you might get a real answer. Otherwise it is like asking the unknown, especially since a one off sale can skew the results.