Bitcoin limited supply explanation (in a single screenshot)

I have been recently asked why there are only 21mil bitcoins and how they are actully generated. It turned out I could not articulate it clearly within 60 seconds, especially the part explaining no hard-coded cap number.
Here is a hint:

The real manifistation of "Software is eating the world" is this line: nSubsidy = 50*COINS which drives the current craze and frenzy.