Where to find historial rental data?

[Ben Bakhshi]

Does anyone know where I can find the following:

Average monthly or quarterly rents, by state, going back as far as possible (hopefully 1978).

I have found so far the following:

http://www.huduser.org/portal/datasets/fmr.html

Which gives annual rents by state going back only a couple of years, and then by Metro area going back to the year 2000.