The blockchain provides a complete record of the movement of bitcoins. So for a given address, you can see how long value has been there, and the addresses that participated in the send transaction, and so on. You can't from there figure out how many coins are still available for circulation, but you can see how much has moved (or hasn't moved) over any period of time (last day, last week, last year, etc). From there you can define circulation statistics, like 'value that hasn't moved in 3 years' or whatever.

For paper money, the fraction that gets destroyed is probably small enough to not matter.