How much would a down payment be for a $14,000 06 Monte Carlo SS?

Ok, so I'm not too big on buying cars from dealerships, so this is gonna be my first time. I'm 18 years old and wanting to finance in an 06 Monte Carlo SS for 14 thousand dollars. I planned on having a co-signer with good credit sign for me because I don't have any credit built up. So, give an estimate on how much the down payment would be, or how much do dealers usually want majority of the time?