It seems like a basic rule of diversification of never keeping all your eggs in one basket, including the the bank. I'm unclear if you're asking how many peopl

It seems like a basic rule of diversification of never keeping all your eggs in one basket, including the the bank. I'm unclear if you're asking how many people keep 90% or more of their total liquid short-term assets in a bank or not. I'd expect most people keep most their short-term liquid assets in a bank since this is usually just their cash on hand. But this is not "all their eggs" considering their long-term non-liquid assets are probably tied up in some sort of retirement vehicles (which are hopefully diversified), and their homes.