Here is recently published study with 200,000 quasars, figure 1 shows the distribution, but only between z = 1 and z = 2.2. (There is a thread about this in General Astronomy forum).
If you want to fiddle around with raw data,
here's Sloan Digital Sky Survey's Third edition of the SDSS Quasar Catalog. Just download the "dr3qso.dat" from the end of that page. Apparently, the catalog contains 46,420 quasars. Have fun!
