There are now more Asians migrating to the United States than Hispanics,  reflecting a  decline in illegal immigration as American employers increase their demand for high-skilled workers. About 430,000 Asians, or 36 percent of all new immigrants, arrived in the U.S. in 2010, according to the latest census data. That's higher than 370,000, or 31 percent, who were Hispanic. A study publis…