At least 96k. There are other suspicious addresses (many of them), but seems highly unlikely that that market could have had such a massive volume (+200k coins), especially considering that SR had only 27k in users funds when it was shut down. Nevertheless:

1) after the media attention to SR the number of black market usets is growing exponentially. BMR is closing because it cannot handle the amount of traffic, in fact there are real concerns about Tor not being able to scale in order to accommodate services with such a huge amount of users.

2) the genie is out of the bottle. Some thought that after SR the "black market use" of Bitcoin was going to disappear. They were delusional. In fact, smart contracts and other applications of the block chains are a killer app for the black market. This is growing, day by day. The insane amount of BTC stolen by such an amateur operation as sheep market is very telling. Compare that to the amount of coins stolen from inputs.io or GLBS. Probably not even Gox is holding 100k BTC of it's users at this moment. Sheep market did.

3) the operator of sheep market was an amateur. He has been doxed. Probably he will end up behind bars soon, and in any case he will have a hard time cashing out the coins. Look at how he is desperately trying to launder them: it's pathetic and amateurish, you just cannot launder 100k coins as he is trying to do because there aren't another 100k from other users to mix you coins with. Either he cashes out in small chunks from localbitcoins, either he is caught very soon.