Coins as a monetary aggregate

Scott Sumner muses that coins might be a good monetary aggregate to look at for what we call "money". We don't have FRED data for the US, but data for Japan is readily available here. Here is the [YoY] growth rate of the supply of coins (the vertical lines indicate recessions in Japan):

Multiply by 100 to get percent. Using coins gets the 1991-2, 1998 and 2008-9 recessions rights, but has a false positive for 1994 and 2005 and misses the 2001 recession.
It doesn't do very well in this model, either:

The better graph uses currency = notes + coins.