On centenary of Polish independence, I noticed that my spendings on rogale świętomarcińskie (St. Martin Croissants) follow peculiar pattern.
November 11th is Polish National Independence Day. Here in Poznań we don't care nearly as much as we do about rogale świętomarcińskie, a local cake (see post from 2015 for details and background). Of course I did buy some.
Out of sheer curiosity, I wanted to see how much I spent on croissants in previous years. Here's the plot of data from 2014 (2017 is missing because I wasn't in Poznań then):
My spendings follow exponential distribution almost perfectly, doubling every time I do buy them. I dread the next year.