High enough, from what we know, to take measures to secure our borders.
Critics of illegal immigration argue that the crime rates of illegal aliens are higher than those of the American population generally, or at least of legal immigrants. The New York Times has denied that illegals commit more crime than other groups, but the paper bases its claim on a Cato Institute study that relies on questionable data. In fact, nobody can calculate with accuracy the crime rates of illegal immigrants or any other social group unless they have reliable data on the size of the group, and we simply don’t know how many illegal aliens there are in the United States.
Nationwide data on crime by illegal aliens is unavailable mainly because most states don’t keep such records.