I have no idea how many hands a dollar passes through in its life, but I'm sure it's plenty. If one new person per week touched your dollar bill in the last year (a conservative estimate), at least 52 grubby mitts have pawed it. Wait, no, it’s 104 — one mitt to spend bill and one to receive it.
According to the Bureau of Engraving and Printing (www.moneyfactory.gov), the life span of various denominations is as follows.
$ 1 .............. 22 months
$ 5 ................ 2 Years
$ 10................ 3 Years
$ 20 ............... 4 Years
$ 50 ............... 9 Years
$100 .............. 9 Years
Guess it's called filthy lucre for a reason.