This implies that much of the money you receive, deal with, use to buy goods/services, etc., is only available on computers and hard drives. Just an estimated 8% of the currency is physical money globally.
All the piles of black money come from inside this 8%. This is a reasonable estimation to which economists seem to agree, not an exact number, however. This low percentage seems ridiculous, but it makes sense to remember that most major transactions are already carried out electronically when you stop thinking.
Banks now store electronically and 92% provide all sorts of transactions made using credit/debit cards and wire transfers. It would be a good idea to revisit all those hacker movies where, in just a few minutes, a nerdy computer hacker manages to siphon off billions.