The average penis length of the Australian man is 15.71cm, while the average girth is 13.2cm (study by Smith et. al.).
An earlier study by Richters et. al. in 1995 found the average penis length for Sydney men was slighyly larger, with a 16 cm penis lenght on average.
Another interestin fact found in that study is circumcised men were on average 0.8cm shorter than the uncircumcised men.
The theory is that the lack of skin in the circumcised penis tethers the penis to the body, restricting it from "expanding" to its full potential size.