What matters most is economic mobility, and my definition of that is what percent of poverty level 20 somethings end up in the top income (and savings) brackets

What matters most is economic mobility, and my definition of that is what percent of poverty level 20 somethings end up in the top income (and savings) brackets by their 30s and 40s. Because it's kind of OK if the bottom fifth of earners is just college baristas and bartenders, or financially independent people just picking up side jobs. I'm pretty sure that's not what is occurring in the US though, because pensions are now nonexistent and our average savings rate has always been horrible.