Actually the exit polls don't attempt to count them in many states. CNN has a good database, they all use the same exit polls. If you review state by state results by religion, you'll note that Jewish only appears in the northeast and Florida. Most states, even states like Illinois and California and New York, are statistly insignificant. With the exception of Florida, in those states where the Jewish vote is recorded, it isn't much different that the general population.
Rechecking, Florida doesn’t have Jewish results either, nor do NJ or CT. They appear to have changed the ranking in some of these states. Essentially you’re taking statistically unreliable numbers from a number of states, actually chosen precincts, and extrapolating them nationally.