Hello

The current number of bitcoins generated today is about 18730000 . I wonder how much of it has been completely lost,
I mean mostly bitcoin which were not transferred for example 10 or 8 may be 6 years.
I am also sure that many people have lost their private keys to their wallets and also do not have access to them.
Can you please suggest or refer me to some site what percentage value we can assume how much of the 18M is currently in circulation
