PHOENIX — The number of Hispanics in Pima County has increased three times as fast as the growth of all other groups combined since the start of the decade.

And the statistics suggest a large percentage of the new residents are migrants — legal or otherwise.

New figures today from the U.S. Census Bureau show more than 60,000 people who identify themselves as Hispanics were added to the county's population between April 1, 2000, when the official count was conducted, and July 1, 2006. That's more than a 24 percent increase, compared with just 7.1 percent for all other groups.

It brings the county's Hispanic population to more than 307,000, or close to one out of every three Pima residents.

The Census Bureau doesn't break down the components of the change. But an analysis of statistics shows only part of the growth can be explained by the number of births.

The state Department of Health Services reports the birthrate of Hispanics is more than double that of white non-Hispanics. That is reflected in the new Census Bureau figures showing the number of Hispanics younger than 5 increased in Pima County at a rate about three times that of all other groups.

Yet among those in their prime working years, the number of Hispanics increased by a much larger margin than others.

Among peoples ages 30 to 40, the number of non-Hispanics living in Pima County actually declined 7.3 percent since 2000, while Hispanics in that age group increased by 21 percent.

Overall, though, the growth statistics from Pima County are low compared with those of Maricopa County, where the Hispanic population has increased by 48 percent since the beginning of the decade. In fact, Maricopa County added 71,000 Hispanics in just one year, more than any other county in the United States, bringing the county's total Hispanic population to close to 1.13 million, just under 30 percent of the total county population.

In terms of overall growth, Yuma County shows the biggest disparity: Since 2000, the non-Hispanic population there has grown just 4.3 percent, versus nearly 30 percent for Hispanics.

But Yavapai, Mohave, Coconino and Navajo counties also are posting Hispanic growth rates at least twice those of the rest of the population.

Only a few counties bucked the trend. One of those is Pinal County, which the Census Bureau lists as one of the fastest-growing in the entire nation. There, the number of Hispanics grew at a slightly slower rate than the 51.1 percent for other groups.

And Santa Cruz County, while posting more than a 13 percent increase in the number of Hispanics since 2000, showed even more rapid growth among others. But more than eight out of every 10 residents are Hispanic.