The world’s super rich got richer in 2014

The world's 400 richest people added some $92 billion to their collective wealth in 2014, according to the Bloomberg Billionaires Index. As of Dec. 29, they were all worth a combined $4.1 trillion.

According to Bloomberg, 2014's biggest earner was Jack Ma, the co-founder of Alibaba, China's largest e-commerce company, who added $25.1 billion to his fortune after Alibaba's initial public offering in September. Microsoft's Bill Gates remains the world's richest man, adding some $9 billion to his net worth, which is valued at $87.6 billion.

In a year of geopolitical instability, not all the mega-rich were so lucky. A clutch of influential Russian billionaires suffered as a result of sliding oil prices and Western sanctions on Moscow. Alisher Usmanov, who entered 2014 as Russia’s richest man, lost a third of his wealth.

In any event, these eye-popping figures should not be a surprise. Global inequality is deepening, with millions of poorer people around the world affected by rising rates of joblessness and decreasing incomes. At the same time, the world's population of billionaires is growing as this Statista chartshows below.

Concern about the yawning gap between the world's rich and poor fueled the astonishing success of French economist Thomas Piketty's book, "Capital in the Twenty-First Century," whose English edition was published last year. Piketty argues that unfettered capitalism concentrates wealth among a coterie of elites and outstrips the growth of labor income. He proposes, among other things, a global tax on capital to force the world's billionaires to pay a fairer share.

Earlier this year, the research arm of Credit Suisse produced this chart showing the distribution of global wealth.

This week, Piketty refused to accept the award of the French Legion of Honor, saying that it wasn't "up to the government to decide who is honorable" and urging French authorities to focus more aggressively on boosting growth in the country.

Ishaan Tharoor writes about foreign affairs for The Washington Post. He previously was a senior editor at TIME, based first in Hong Kong and later in New York.