Every year, Forbes magazine releases a list of the 400 richest Americans and today saw the release of a new edition. Their rankings aren't official or necessarily 100 percent accurate, but it is pretty much the best source that exists in the world for information about America's hyper-wealthy. These days, the subject of the rankings are no mere curiosity — growing inequality means that moves at the tippy-top of the wealth spectrum have some real meaning for American society. Here are nine key facts learned from the new release.

1) The 400 wealthiest Americans control $2.29 trillion in wealth

This should probably be considered a low bound estimate. As Gabriel Zucman and other researchers have found, the use of tax shelters by hyper-wealthy individuals naturally leads to undercounting of their wealth by government and media sources. Some individuals' financial holdings are fairly transparent (comprised overwhelmingly of shares of stock in a company they founded) but beneficiaries of inherited wealth or simply people who've been wealthy for a long time tend to have murkier asset allocations. The total wealth of the very wealthy is about 2.8 percent of all wealth in America which might sound small but 400 people is less than 0.00013 percent of the entire population.

2) That's a $270 billion increase from last year

Very wealthy people tend to own many shares of stock, so the wealth of the very rich has recovered sharply from the recession and reached a new all-time high even as average incomes stagnate.

3) Of the previous year's 400 richest Americans, only 36 saw their net wealth fall

"A rising tide lifts all boats" is false of the economy as a whole, but generally true of billionaires. Once you amass a large diversified pool of financial assets, it doesn't require any particular skill or judgment to see its value continue to grow any time global stock markets generally rise.

4) The average net worth of the Forbes 400 is a record $5.7 billion, an increase of $700 million from last year.

That's a bit slower than the 14 percent average increase across the entire American population. America's most average billionaire is Stanley Kroenke, whose $5.7 billion in assets include large ownership stakes in Arsenal, St Louis Rams, the Denver Nuggets, the Colorado Avalanche, and other pro sports teams.

5) You need $1.55 billion to make the cut, up from $1.3 billion last year

This is an all-time high in nominal terms, and the rate of increase of over 20 percent is much faster than the underlying rate of inflation.

6) At least 113 US billionaires were too poor to make the list

Probably time for Forbes to consider switching to a Forbes 500 list to leave no billionaire uncounted.

7) Bill Gates is the richest American for the 21st straight year

Gates seems like a genuinely good person who is dedicating most of his financial wealth to useful charitable endeavors. Nonetheless, the fact that he's had a generation-long run at the top spot (and shows no sign of losing it) tells us something about social mobility and economic dynamism. That this wealth is deeply entangled with government-created copyright and patent monopolies is also telling..

8) Mark Zuckerberg's wealth rose $15 billion last year, the biggest increase

Facebook is very popular, which you have probably noticed.

9) Nick Woodman, founder of GoPro, was the biggest percentage gainer at 200%

GoPro makes cool cameras that let you make high-quality digital recordings in unusual situations at prices that, while high, are incredibly affordable compared to traditional film. Here's POV footage of a golden eagle in Mongolia: