many of them undocumented -- make up almost 4 percent of the total U.S. population. Researchers found that 6.8 percent of recent adult Mexican immigrants assessed their own health as fair or poor compared to 10.6 percent of U.S. born whites, and just 2.6 percent have diabetes. After 15 years in the United States, 15 percent of Mexicans said their health was fair or poor and 7.7 percent had been diagnosed with diabetes. More than half of the 10.2 million Mexican immigrants living in the United States do not have health insurance and lack of documents due to an uncertain legal status means they are often ineligible for public health insurance. In their homeland, most formally employed Mexicans have basic public health coverage but millions in the countryside or in informal jobs are not covered. Elena Zuniga, one of the authors of the report who works for Mexico's National Population Council, said that good health among immigrant workers had benefits for both Mexico and the United States. "Without good health, Mexican immigrants cannot work in the physically demanding occupations where many are concentrated such as agriculture and construction," she said.