Astronauts!

The odds of becoming an Astronaut are approximately
1 in 13,200,000 (0.0000075 %)

Keep in mind that not ALL astronauts are chosen through a lottery so if you really want it you probably have to work out and train on one of those spinning things. But the odds of becoming a space chimp are closer to 1 in 8.

(http://chicago.metromix.com/home/photogallery/what-are-the-odds/890340/photo/890348)