At first glance, China appears to be a far more unequal country than the U.S. Its hundreds of billionaires tower over the emerging middle class, while millions of others live on less than $1 a day.

But new data shows that inequality in the U.S. is actually worse than it is in China.

In a paper published by the National Bureau of Economic Research, economists Facundo Alvaredo, Lucas Chancel, Thomas Piketty, Emmanuel Saez and Gabriel Zucman found that inequality in both the U.S. and China has grown rapidly over the past few decades.

In China, the top 1 percent earned 13 percent of personal income in 2015 — double their share in the 1980s. In the U.S., the top 1 percent earned 20 percent of income. That's also roughly double the level from the 1980s.

Of course, measuring the incomes of the wealthy Chinese is an especially difficult task, since so much of their money is hidden. As the paper notes, "our estimates should likely be viewed as lower bounds, due to tax evasion and other limitations of tax data and national accounts in China."