Today, as in the past, within a country at a given time those with higher incomes are, on average, happier. However, raising the incomes of all does not increase the happiness of all. This is because the material norms on which judgments of well-being are based increase in the same proportion as the actual income of the society. These conclusions are suggested by data on reported happiness, material norms, and income collected in surveys in a number of countries over the past half century.
Easterlin, R. A. (1995). Will raising the incomes of all increase the happiness of all?. Journal of Economic Behavior &Organization, 27(1), 35-47.