Wellbeing varies hugely in the human population. About 80% of this variance is within countries and about 20% is between countries. Between 1980 and 2007 average wellbeing rose in more countries than where it fell. But since 2008 wellbeing has fallen in roughly the same number of countries as where it has risen. Since 2006/8 there has been a large worldwide increase in negative affect and in stress. In the US the inequality of wellbeing is one of the highest in the OECD, whereas Europe (since 2008) now has lower wellbeing inequality than any other region.

Average wellbeing is very similar for men and women in almost every country. It declines with age in most parts of the world but in North America and Europe it improves after mid-life. Average wellbeing is below average for most ethnic minorities in most countries. Children’s wellbeing is lower in the UK, the United States and Japan than in most other OECD countries. Meanwhile, adult life-expectancy has risen in most regions of the world, especially in Sub-Saharan Africa. So the Wellbeing-Years (WELLBYs) which a person now born can expect have increased since 2006–8 in all regions of the world.