Unemployment vs. Disapproval of Presidents

I really like the Presidential Power site that fellow blogger Frank Franz (Panthers Fan) mentioned below.  It led me to an article with charts comparing unemployment and disapproval of presidents.  That led me to this article and charts on all presidents from Reagan through Obama.  The charts and article from Pew, of course, lend credence to the fact that Obama is in trouble for his re-election if he doesn't get unemployment down.