I'm curious, where are you heading with this counter argument? That perhaps, something like 900k Americans living in Europe are in the US Armed Forces, leaving 100k regular US citizens. So then, if all 5k of the US citizen renouncers worldwide are in Europe, then 5% of the remaining 100k _does_ count as "many"?
Quick research: Kaiserslautern Military Community has ~50k people. https://en.m.wikipedia.org/wiki/Kaiserslautern_Military_Comm...
Now that's the largest, but by far not only location with US Military presence in Europe.