Do you have much evidence that this is a real problem on the scale of the US population? I would imagine a tiny percentage of citizens were anchor children (i.e. people whose parents came to the US purely to give birth to them, then left again)
Sources for your numbers? I'm curious to learn more about how widespread this issue is. I personally have heard of 2-3 cases in my small social circle, so to me it feels more common. But I am having trouble finding actual numbers.