Only an estimated 8 per cent of currency globally is physical money.
Banks store electronically too and the 92 per cent includes all kinds of transactions done using credit/debit cards and wire transfers. Might be a good idea to revisit all those hacker movies where a nerdy computer hacker manages to siphon billions off in just a few minutes.
All the black money piles come from within this 8 per cent. This is a fair estimate that economists seem to agree on though, not an exact figure. This low percentage seems absurd but when you stop to think, it makes sense considering that most large transactions are done electronically anyway.