But that's not how economic mobility is generally measured. It's usually movement from bottom to top quintile. The measure is relative mobility within a society, not absolute mobility.
But the WEF reference for the grandparent uses a "social mobility index" which includes such factors as: "Adolescent birth rate per 1,000 women", "Pupils per teacher in pre-primary education (%)", "Extent of staff training (1–7 best)", "Internet users (%)", "Meritocracy at work (1–7 best)", so it's clearly quite subjective when it comes to "social mobility".
But the WEF reference for the grandparent uses a "social mobility index" which includes such factors as: "Adolescent birth rate per 1,000 women", "Pupils per teacher in pre-primary education (%)", "Extent of staff training (1–7 best)", "Internet users (%)", "Meritocracy at work (1–7 best)", so it's clearly quite subjective when it comes to "social mobility".