NEW YORK — Add an extra zero to the ranks of the millionaires club.

The number of people around the world with at least $1 million in assets passed 10 million for the first time last year, according to a report. And their bank accounts are growing even faster.

The combined wealth of the globe's millionaires grew to nearly $41 trillion last year, an increase of 9 percent from a year before, Merrill Lynch & Co. and consulting firm Capgemini Group said Tuesday.

That means their average wealth was more than $4 million, the highest it's ever been. Home values were not included in asset totals.

"The growth of their wealth is outpacing the growth of their population, and that's a trend that's going to continue in coming years," said Ileana Van Der Linde, a principal with Capgemini.

The ranks of the wealthy are growing fastest in the developing economies of India, China and Brazil. The number of millionaires in India grew by about 23 percent.

The United States still reigns supreme when it comes to fat wallets, though: One in every three millionaires in the world lives in America. Combined, Africa, the Middle East and Latin America account for just one in 10.

All told, there were about 600,000 more millionaires in the world in 2007 than in 2006, for a total of about 10.1 million. That's a 6 percent increase from the previous year. But it still represents less than one-fifth of 1 percent of the world's 6.7 billion people.

The rarefied group of the superrich — those with at least $30 million in assets — got richer, too. There were 103,000 of them around the world last year, 9 percent more than the year before.