I heard a number of years back that the US penny circulation is troubled because too many pennies are given in change, put in a pocket, get home, are thrown on a dresser or on a jar or something, and never used again. Because, if you ever do grab up some change, what do you do, you pick out the quarters, right? So it's not like there's not enough pennies out there, it's just that people are unintentionally hoarding them.