A pretty crude way of working it out, but I wanted to know this also. The computer room where I work has 20 15" TFTs, and I counted 3 of them with dead or stuck pixels, not too bad really. I assume though that the percentage increases with larger displays. Hence the difficulty some people seem to be having getting the "perfect" Dell 2001FP.
My 1800FP also came with one stuck red subpixel, however it seems to have corrected itself after 2 months.