WASHINGTON (Reuters) -- In the world's biggest economy, one in eight Americans and almost one in four blacks lived in poverty last year, the U.S. Census Bureau said on Tuesday, both ratios virtually unchanged from 2004.

The survey also showed 15.9 percent of the population, or 46.6 million, had no health insurance, up from 15.6 percent in 2004 and an increase for a fifth consecutive year, even as the economy grew at a 3.2 percent clip.

It was the first year since President George W. Bush took office in 2001 that the poverty rate did not increase. As in past years, the figures showed poverty especially concentrated among blacks and Hispanics.

In all, some 37 million Americans, or 12.6 percent, lived below the poverty line, defined as having an annual income around $10,000 for an individual or $20,000 for a family of four. The total showed a decrease of 90,000 from the 2004 figure, which Census Bureau officials said was "statistically insignificant."