I tried to find a video of this on youtube, which I could not. I did however find a video of him making the same mistake 3 weeks ago in Pennsylvania, this time confusing it with North Carolina 🙄
In the speech, he said it was a 2000% increase in immigration in a small town. So if that town has something like 2 immigrants in a decade (probably a pretty realistic number), then that means there were probably a handful of immigrants in that year (2000% of 0.2 is 4).