a world of happiness

For work, I'm trying to figure out a new display for our window, and one of my ideas involves finding a map. (How I wish I personally owned a large wall map. Wait a second...I do. Now where is it?) But hey, I'm digressing, and I just started...

I encountered on google image search the following map: world of happiness.

I wonder what criteria they used to say that the US is very happy, Brazil is averagely happy, and Chad is unhappy. For some reason, Russia is unhappy, but China is only low average happy. Some countries--like Greenland, North Korea, and Somalia don't even get a shade that evaluates their happiness. I would also like to point out that many people in America are very UNhappy, whereas many people in impoverished nations are incredibly happy.

So happiness, being a strange and elusive concept, continues to be...strange and elusive. I don't understand the purpose of making a map like this. (Some cartographers have too much time on their hands.) I'm sure if I could find the original site that this picture was taken from, it would make a lot more sense. Or, if I could interview those scholars who originally created it, I could understand its purpose and intent. In the meantime, I opt for confusion and homework.