I'm not sure what that metric is supposed to prove? That Switzerland has a higher number of rich US expats who want to avoid paying US taxes than other countrie

I'm not sure what that metric is supposed to prove? That Switzerland has a higher number of rich US expats who want to avoid paying US taxes than other countries do? It's very difficult to get Swiss citizenship in the first place, so it makes sense that it's mostly well off US citizens who are able to get Swiss citizenship, and are thus able to renounce their US citizenship.