I found this article on the web https://www.saznajnovo.com/2013/04/proverite-koliko-struje-potrosi-vas-racunar/ and following instructions I calculate that my PC cost me around 170€ per year (with monitors). Is it possible that the computer consumes so little power? It's realy cheap, right? Also I saw that numbers at the bottom of article in Serbia it cost around 20 EUR per year?!