[T]he whole World Values Survey, which grew out of the European Values Survey in 1981, is concerned with tracking value evolution across the globe, which is commonly seen as a two-step process.  Though it is often simply referred to as "modernization," a more precise description differentiates between two stages.

The first is modernization, which involves the transition from agriculture to industrial societies, dominated by increases in income that translate into increased well-being. The second is post-modernization, which involves a shift in emphasis toward quality of life,  self-expression and self-determination. . . .

The two-phase structure is very evident in the following graph of GNP and perceived well-being:

which is schematized thus: