I just dumped a huge amount of accumulated household change into the sorting machine at our credit union. I was impressed that it managed to count all the US change while spitting out two Canadian coins and a taka.
Here’s what was in there:
- 354 pennies
- 99 nickels
- 163 dimes
- 129 quarters
The source was a salad bowl that sits on our bookshelf into which I periodically empty my pocket when I feel it’s too heavy with change. I don’t think I ever take anything out. So this should be a fairly accurate estimate for the steady-state proportion of different coins in my pocket.
On the other hand, here’s the number of coins of each denomination in circulation in the US:
- 13b pennies;
- 841m nickels;
- 1.8b dimes;
- 1.1b quarters.
So the relative proportions of nickels, dimes, and quarters in my salad bowl are just about equal to what you find in nature. But I have very few pennies. Why? Because I actually make an effort to pull out a number of pennies from my pocket equal to price modulo 5, when I pay by cash. Whereas I seldom try systematically to keep down the number of nickels, dimes, and quarters I carry around. I can’t say I have any particular rationale for this behavior, but it explains the statistics of my salad bowl.
But wait: the numbers on the site I linked to are surely wrong. 1.1b quarters is about 4 per American, way too low — despite what the site claims, I think those must be the number of coins produced per year. And according to Wikipedia, those numbers fluctuate wildly from year to year. In 2008, the Mint made more than twice as many quarters as dimes, but in 2011 there were almost four times as many dimes as quarters. And the total number of coins produced, which had held steady at about 14b/yr through most of the decade, dropped to 3.5b in 2009 and rebounded to 8.2b last year. What’s going on? It looks like coin production is at least to some extent correlated with the strength of the economy. It dropped to almost nothing during the Depression. The song “Brother, Can You Spare a Dime” was written in 1931. I never knew that they actually made no dimes in 1932 or 1933!