A recent letter on this page cited statistics from the Federation of American Immigration Reform, an organization tagged as a hate group by the Southern Poverty Law Center in 2008.
FAIR is a lobbying organization that plays fast and loose with its tax status and spews out dubious "facts" that it sources from its sister organization, the Center for Immigration Studies.
CIS' main function is to produce anti-immigrant "studies" that are either outright false or lack any supporting evidence. The founder of FAIR and CIS -- John Taunton -- a holocaust denier and noted white nationalist, has been fomenting racial animosity since the '90s.
In short, I wouldn't believe anything coming from this bunch even if their tongues were notarized.