I’ve been saving all my cent coins in a jar for the last few months, with the purpose of counting up the years on them to see what sort of distribution there is. Today I counted my jar of 185 pennies, and the results were not entirely what I expected. I should mention that these are Canadian coins, as I am Canadian after all.
I’d gone into this assuming that 2010 would have the most, then 2009, then 2008, and so on. Some sort of exponential function would make sense. I wasn’t sure about 2011 because I don’t know when the mints make coins, or if they’re consistently minted throughout the year or if there’s one day/week/month where the penny machines get cranked up to the 11 setting.
To start with, here’s the raw data in case anyone else wants to take a look: raw_penny_data. In addition to the year:count data it also includes a cumulative count column and a weighted average column. Feel free to do whatever you want with it, citing it if you use it somewhere else of course.
And here’s the resulting graph from Excel. I’ve add in some labels with Photoshop on some of the relative peaks:
I knew 2010 would be high, but holy shit that’s a big peak. And what’s up with 1994? I’ve heard before that after 5 years 50% of pennies from a year have dropped out of circulation. 1994 has held in there pretty well, and 1995 is right up there too. I wonder if there was a surge in penny production over that timeframe? Also, 1987 looks relatively large when compared with the other counts around it. The overall trend looks exponential though, as predicted.
After seeing the results, I think I’m going to continue saving my pennies and add the new data at the end of the year, to see what a larger sample size will produce. I’m curious if the 1994 spike will become absorbed with a larger sample size, or if there’s actually some reason for there to be more pennies from that area.
Also, not relating to the data, I found a single penny that completely lacked a date. I’ve never seen that before. It looked like a 1995-2005ish penny based on the level of wear and tear, and with the exception of the lack of a date it’s identical to all the other pennies. I couldn’t find any information on these type of pennies either, maybe it’s some sort of defect? At any rate, it’s not a common feature on Canadian coins so it might be worth something. I intend to hang onto this dateless penny.
Here’s a photo of the full penny pile:
And the dateless penny. The date is normally right about the CA in Canada, but is nowhere to be found on this coin:
That’s all for now.