For years now, politicians and pundits have touted education as the key to economic advancement. And Millennials are the best-educated generation in American history. But we're not even close to being the best-paid. New Census data shows that despite the march of technology and our college degrees, we earn less than our parents did at the same age. The Census Bureau today released new data from its American Communities Survey, showing that today's 18-to-34-year-olds are earning less today than the same age group in 1980, 1990, or 2000.

As of 2009-2013 (the span that the new data covers), millennials had median earnings of around $33,900, down from around $37,355 in 2000. That's a decline of around 9.3 percent in just over a decade. And while other Americans' earnings have also stopped growing since 2000, Census data suggests it wasn't so bad for them. From 2000 to 2011, median earnings for all full-time, year-round American workers held roughly steady, at around $43,600. This older group naturally has a higher income than the lower population on its own, but what's fascinating is that things haven't fallen off as much for them.

Those people's earnings don't seem to have fallen off like the young adults' earnings have. So what's going on? A couple of tables from think tank Demos help shed some light on it. This is what median earnings looked like for young bachelor's degree holders over the last 30 years.

And here's what it looks like for high school graduates:

This only looks at 25-to-34-year-olds, but it seems to indicate that one share of the population is taking this hit particularly hard: men who haven't gone to college. A few things could be going on here: one is the decline of middle-skill jobs, like many manufacturing jobs, that were once common high-school-educated men. Or maybe men are being held back by social and cultural forces, like David Leonhardt wrote earlier this year — single-parent families, harmful gender norms, and poor early school performance get boys off to a bad start. Of course, it's also important to keep in mind that high-school educated women, who haven't lost as much ground, still remain far behind, with median earnings of $24,000.

This illustrates the ugly choice that the last few decades of high school graduates have faced — everyone thinks of college as the ticket to prosperity, so America's young people have increasingly invested in college degrees. And it's true that those graduates are doing way better than those without degrees, both in terms of income and employability. But it's mostly paying off because the economic situation just keeps getting worse for people with only a high school diploma. For millennials, this means investing four or more years, plus tens of thousands of dollars, to get a degree whose value isn't really increasing much. The whole generation has been stuck on a sort of cruel economic treadmill: working harder and harder without really getting much further ahead.