PETN or, in other words, Pentaerythritol tetranitrate, is a vital ingredient of the (in)-famous explosive Semtex. It was also the chief ingredient of the explosive charge used, thankfully without success, by the latest airplane bomber-to-be, Farouk Abdul Mutallab.
It is believed Farouk Abdul Mutallab had moulded a quantity of the explosive powder to his body, sewn into his underwear in a six inch packet. He then attempted to detonate the device using a syringe containing a liquid, which was later recovered on the aircraft by FBI agents. Officials believe tragedy was only averted because the makeshift detonator failed to work properly.For curiosity sake, I have checked on Google Trends how the interest in PETN behaves, geographically speaking, and the result was somewhat surprising (click to enlarge):

It might be of interest that small (population-wise) countries like Israel and Finland generate significant traffic too, but then Google lumps Israelis and Palestinians in one statistical lump. Finns - who knows, perhaps they need high explosives to deal with tree stumps or summat.
You explain Switzerland, I get tired quickly.