how long does it usually take for an outside company to conduct a background check?

i've submitted my suplimental application to the city, i've filled out the online questionare from the background check, i've been fingerprinted at the police station.

i was fingerprinted on the 13 of last month, and had the suplimental application and online questionare taken care of by the 19th. had my polygraph and psych tests in between those dates.

from scuttlebutt i've heard from asking around, they are down to between 70 and 80 candidates before the poly, psych and background. (for somewhere between 1 and 12 positions)

my question is, how long should the next step of the process take? can i realisticly expect to hear from the city before the end of the year?