U.S. Population: 311,915,771
U.S. Population on food stamps: 45,753,078
Percentage of U.S. population on food stamps: 14.67%
Yeah, having more than 1/7th of our population on food stamps seems like a bad sign.
Edit:
For future reference, in 2006, the average household on food stamps had a size of 2.3 people and a gross income of $673 per month ($8,076 per year).
Also, illegal immigrants and some legal immigrants are excluded from food stamps, so these figures underestimate total poverty.