It is a relatively well-known fact that the United States has become one of the most unequal countries in the developed world when it comes to income.

And that's just labor income. Add in stock dividends, interest, rent and business profits, and a haunting picture emerges — the U.S. is approaching a level of inequality not seen since the Great Depression.

See also: A French Economics Book Is Dominating Amazon Right Now

That is the conclusion from two economists who have compiled a century's worth of data on wealth creation in the U.S in a paper entitled "Exploding wealth inequality in the United States." Emmanuel Saez and Gabrial Zucman found that the share of overall wealth held by the top 0.1% of those in the U.S. had grown to nearly equal the bottom 90%.

The paper comes at an important time for the study of inequality. French economist Thomas Piketty made headlines earlier this year within academic circles — and across the world — with his book Capital in the Twenty-First Century. He asserted that wealth is rising faster than income in developed countries due to a systemic issue. Put simply: The rich are getting richer simply by being rich.

The rich have not always owned such a big chunk of America. Saez and Zucman's data highlights how the post-Depression era saw a massive transfer of wealth from the rich to the rest of the country that topped out in the mid 1980s. Since then, the top 0.1% has made major gains.

It can be a little difficult to grasp just how small 0.1% is in comparison to 90%. The pie chart below helps to illustrate that disparity. "Even" shows how the split of wealth would look if the 0.1% had 0.1%; the 2012 number highlights the actual split.