Actually, every bank has the right to set its own rate.
However, these are almost always prime rate + whatever.
Since nearly ever bank has FDIC insurance, they all pretty much are under the thumb of the Federal Reserve. Only a few risky, venture capital firms will waddle out w/o federal support of some kind.
Right now, the US prime lending rate is down to 4% (I believe they got the most recent cut asked for).
Generally, the whatever part is determined by 1: the type of loan, and two: the credit-worthiness of the borrower.
The law requires the rate to be prominently disclosed on all documents about the loan.
That's why you see those little sheets with the giant print in all the credit card mailers and whatnot.
So, there is not generic rate. The averages in the US are between 8% and 14%, depending on the type of loan and whether it is federally subsidized. It varies slightly from region to region, generally being bent down by building booms (more homes = more loans).
We can't stop here! This is bat country!