Former President Felipe Calderon declared last year that Mexico is becoming a middle-class country.

Not so fast, says the official statistics institute.

A National Institute of Statistics and Geography analysis released Wednesday says nearly 60 percent of Mexico's estimated 112 people still belonged to the lower classes in 2010. It says that the middle class grew by 4 percentage points, to almost 40 percent of the population, between 2000 and 2010. Just 1.7 percent were considered part of the upper class.

The institute didn't list precise criteria for defining middle class. But it says those households generally have a computer, spend at least $340 every four months to eat out, have a credit card, at least one member with formal employment, and are headed by a high school graduate.