From a review of Happiness: Lessons from a New Science by Richard Layard, in The Economist:
For the past half-century, those lucky enough to have been born in a rich country have had every prospect of growing richer. On average, incomes in Britain, America and Japan, adjusted for inflation, have easily doubled over that time. On top of this come the benefits of longer lives of better quality, thanks to advances in medicine and to a plethora of consumer goodies making living easier and more enjoyable. You might, even, expect folk to be a great deal happier today than in the 1950s.
You would be wrong, according to many surveys taken in rich countries. These tend to show that, once a country has lifted itself out of poverty, further rises in income seem not to create a meaningful rise in the proportion of people who count themselves as happy. Since the 1950s, for example, the proportion of Americans who tell pollsters that they are “very happy” has stayed constant at around 30%, while the proportion who say that they are “not very happy” has barely fallen. Explaining this paradox, and offering suggestions for increasing the supply of happiness, is the aim of a new book by Richard Layard, a professor of economics at the London School of Economics and a Labour peer.