What do you mean 6 percent? Do you mean exactly or in general? 

Also little known thing, that the fed loans money to private banks at a lower rate than they pay interest; so banks can borrow money from the fed, then put it back in the fed and earn a profit. 

Also the interest rates that banks used is essentially made up out of thin air, most interest rates are based on LIBOR (which has been known to be manipulated, see scandal) and this is the rate that banks charge one another on private markets to borrow from each other.   Also if you notice another thing is that the fundamental premise of banking is simple right?

Bank takes deposits and then they loan the money based on those deposits; but in reality they will loan far beyond what they get from those deposits and they get that money from the federal reserve and borrow it from other banks.