Umm, it means that the immigrants are probably INCREASING their median incomes, so it is not a downer for them. And it DOESN'T mean you whitey's are declining in your incomes, so it is not a downer for you.
This is one of those statistics that is actually saying something quite different than the great unwashed think it says. But ya know, gotta hate those wet backs -- can't have logic get in the way.
I certainly don't hate "wetbacks" as you called them. The point is, the media lies.