In this week’s magazine, I’ve got a lengthy piece about “Capital in the Twenty-first Century,” a new book about rising inequality by Thomas Piketty, a French economist, that is sparking a lot of comment and debate. (Brad DeLong has a useful summary of some early reviews.) I’ll go further into that discussion in future posts, but first I thought it might be useful to portray the gist of Piketty’s story in a series of charts.

The charts aren’t merely illustrative: they are an essential part of Piketty’s contribution. Fifteen or twenty years ago, debates about inequality tended to be cast in terms of clever but complicated statistics, such as the Gini coefficient and the Theil entropy index, which attempted to reduce the entire income distribution to a single number. One thing that Piketty and his colleagues Emmanuel Saez and Anthony Atkinson have done is to popularize the use of simple charts that are easier to understand. In particular, they present pictures showing the shares of over-all income and wealth taken by various groups over time, including the top decile of the income distribution and the top percentile (respectively, the top ten per cent and those we call “the one per cent”).

The Piketty group didn’t invent this way of looking at things. Other economists, such as Ed Wolff, of New York University, and Jared Bernstein and Larry Mishel, the creators of the invaluable State of Working America series, have long used similar charts and tables in their publications. But partly by using new sources of data, such as individual tax records, and partly by expanding the research to other countries, Piketty and his colleagues have deployed their charts to reshape the entire inequality debate.

For a long time, that debate was almost entirely focussed on what was happening to median incomes. That inevitably led to discussions of globalization, skill-biased technical change, and policies focussed on education and retraining. Now, thanks to Piketty et al., the remarkable gains of those at the very top can’t be avoided. And this means that the issues of politics and redistribution can’t be avoided either.

The first chart is a simple one, and it concerns the United States alone. It tracks the share of over-all income taken by the top ten per cent of households from 1910 to 2010. Broadly speaking, it’s centered on a U shape. Inequality climbed steeply in the Roaring Twenties, and then fell sharply in the decade and a half following the Great Crash of October, 1929. From the mid-forties to the mid-seventies, it stayed pretty stable, and then it took off, eventually topping the 1928 level in 2007. (The chart shows the share of the top decile falling back a bit after the financial crisis of 2007 to 2008. New figures for 2012 from Saez, which came out too late to be included in Piketty’s book, show the line hitting another new high, of more than fifty per cent.)

The second chart shows the share of income taken by the one per cent over the same period, and the teal line, which includes income of all kinds, has the same U shape. (Once again, the 2012 figures, which aren’t included, show another step up.) The top percentile hasn’t taken such a large share of over-all income since 1928. Interestingly, the recent rise in its share is a bit less dramatic when the analysis is confined to wage income. The difference between the bottom line (wage income) and the top line (total income) is accounted for by income from capital—dividends, interest payments, and capital gains. Because they own a lot of wealth, the one-per-centers receive a lot of their income in this form.

Chart Three expands the analysis to what Piketty calls other “Anglo-Saxon countries”— Australia, Canada, and the United Kingdom—and it confirms that rising inequality is a global phenomenon. Since 1980, the share of over-all income going to the one per cent has risen sharply in those three nations, too. However, the United States still comes out as the winner of the inequality race. That’s perhaps not too surprising: we tend to think of the United States as a very unequal country, but it’s worth noting that this perception wasn’t always accurate. The chart shows that, ninety years ago, the United States and Canada had roughly the same amount of inequality, according to this measure, while the United Kingdom was a markedly less equitable place. Today, though, the U.S. has few challengers. Even in terms of income generated by work, Piketty notes, the level of inequality in the United States is “probably higher than in any other society at any time in the past, anywhere in the world.”