It will depend totally on how you ride it. I've just had a set fitted and would expect between 6 to 8,000 out of it from experience of them on previous bikes.
I usually get about 6k from the rear. I've just replaced my front and rears with Conti trail attacks as they were cheaper than 020. To early to say if any better or worse.
The rear 020 I've just replaced had done about 4.5k but was very squared off, and probably would not have lasted the next long trip I've got planned. The front tyre had done about 8k and was down to about 1.5mm.