There appears to be a single main diagonal that includes China, Russia, Italy, France, and Germany. Above that diagonal are countries where it takes less money

There appears to be a single main diagonal that includes China, Russia, Italy, France, and Germany. Above that diagonal are countries where it takes less money to achieve that same satisfaction as those on the main diagonal. Apparently, Brazil, Mexico, India, and Nigeria get more satisfaction for the same level of income. That leaves Japan and Iran as the outliers where you get far less satisfaction for a given income level. The slope of the lines is also interesting. Nigeria and Brazil stand-out as two places where income matters less it does others. The US and UK are also flatter (less income elastic) than the main diagonal.