Australian Department of Immigration and Multicultural and Indigenous Affairs Annual Report 2001-02
is an older report as you can see and an agency earning their fee might even be able to do a search for something more recent.
And I knew I had seen Service Standards somewhere:
If the % achievments are anything like what they were in 2001 -2, that'll give some idea but immi are not really going to be telling people that we'll aim for 9 months but might take 15.
Also saw a report for 02/03 on immi.