Last night I was searching the St. Louis Fed's economic data website for cats, because what's better to do on a Friday night at home than try to combine your two favorite things on the internet, cats and charts?

The closest FRED gets to cat data is pet food inflation. I took a peek and found something really interesting: pet food prices spiked during the recession. It's not just a little spike. Prices were up nearly 20% year-over-year in 2009.

Human food prices went up a lot during that time, too, but nothing like the pet food prices.

I had a lot of responses to the chart on Twitter (we all had very exciting Friday nights), but no really good explanations for why this might have happened.

Do you have any ideas?

Here's the chart:

As an aside, it's also interesting that pet food prices have gone down in the last year.

Anyway, the point is I'd like to solve this mystery. If you know why pet food prices jumped so high in 2009, get in touch! Tweet @shaneferro or email me sferro@businessinsider.com.