Ten years ago, the world had 147 dollar billionaires. Five years ago, it had 274. Now, according to last week's issue of Forbes magazine, which makes an annual compilation of the super-rich, the number has increased to 447. In the past year alone, the number of billionaires has risen by 25 per cent.
Meanwhile, the poor get poorer. John Kavanagh, of the Institute of Policy Research in Washington, DC, calculates that the billionaires' combined wealth exceeds the annual income of half the world's population - a total of nearly 3 billion people.
"Globalisation," says Mr Kavanagh, "has given more opportunities for the extremely wealthy to make money more quickly. These individuals have utilised the latest technology to move large sums of money around the globe extremely quickly and speculate ever more efficiently.
"Unfortunately, this technology makes no impact on the lives of the world's poor. In fact, globalisation is a paradox: while it is very beneficial to a very few, it leaves out or maginalises two-thirds of the world's population."
Forbes, the house journal of the international rich, puts it rather differently: "Great fortunes are made in times of rapid social, technological and economic change by those who grasp the meaning of the change early on. That's why the big fortunes matter. They spring up like plants after a spring rain wherever economics comes to life and there is solid economic progress."
So who are the super-wealthy, how do they make their money and where are they based? In a preface to last week's issue, James Michaels, the editor of Forbes, admits: "It's not an exact science and our numbers are, well, roundhouse numbers."
The magazine's researchers had to ferret out hidden money (Europeans particularly tend to be reticent) and evaluate all kinds of properties in many countries. They also had to discount those who exaggerate their wealth. For example, Tan Yu, the Philippine property tycoon, reckoned he was worth at least $26bn, which would make him comfortably the richest person in the world. Forbes decided he was worth nearer $7bn. Sometimes, the magazine's criteria are obscure (shouldn't the Sultan of Brunei be in there somewhere?) and, in many cases, the billions are held by families rather than by an individual.
Some broad conclusions are possible, however. The United States still has far more billionaires than any other country - 149, against 96 five years ago.
Germany's 51 billionaires account for nearly half all those in Europe. Forbes lists just six billionaires for the UK - David Sainsbury and family; Garry Weston and family (who run Associated British Foods); the Schroder banking family; the Moores family (owners of Littlewoods); the Duke of Westminster and family; and Richard Branson. We are given a half-share with France (which has 14 other billionaires) in the $2.5bn fortune of the Rothschild family.
The countries to watch are in Asia. Not Japan: it still has 41 billionaires, exactly as it did five years ago (though they are not the same people). But the rest of Asia - Thailand, Indonesia, Korea, Malaysia, for example - now has 82 billionaires, treble what it had in 1991. Forbes points out that many of the new US fortunes are built on computer and communications technologies. In Asia, however, the new money tends to come from property development, energy and natural resources. "In this respect," says Forbes, "Asia mirrors the US of a few decades back."
Latin America, too, is coming up fast, with 39 billionaires, against eight in 1991. Ecuador, for example, has its first billion-dollar fortune, made by 45-year-old Alvaro Naboa from bananas and property. (Mr Michaels observes that he has "an ego the size of one of his refrigerated cargo ships".) But the whole continent of Africa has only two billionaires, both in South Africa.
Here, then, are the world's 10 richest people as identified by Forbes (some families, categorised among the billionaires and listed below, are worth more) with, for each one, a telling comparison:
William Henry Gates III (US). His $18bn fortune is greater than the 1993 GDP of Syria ($17.2bn). Aged 40, he owns 36 per cent of Microsoft, the business he co-founded in 1975. One of his companies, Continuum, is buying up the computer rights to thousands of paintings, including 2,000 of the National Gallery's.
Warren Buffett (US). His $15.3bn fortune is worth more than Ecuador's annual GDP ($14.4bn). His genius is for market speculation. Since he started in 1954, he has never suffered a single losing year, a feat once thought impossible.
Paul Sacher (Switzerland). His $13.1bn wealth equals the annual GDP of Uruguay. Now 90, he recently retired from the board of Roche, the drug company. He started life as a conductor, but then married the heiress to the Hoffman Laroche chemical empire. He has always been a generous patron of the arts, backing such figures as Stravinsky, Bartok and Picasso.
Lee Shau Kee (Hong Kong). His $12.7bn fortune almost matches Vietnam's annual GDP ($12.8 bn). Like most very rich people in the colony, he is a property developer, whose Henderson Land development has increased seven times in size in the last six years. Now, he has a new company expanding into China.
Tsai Wan-lin (Taiwan). His $12.2bn fortune exceeds the annual GDP of Yemen ($12bn) His family's flagship is Cathay Life Insurance, whose shares have gone up 74 per cent in the past year, despite government efforts to open the insurance market to foreign competition.
Li Ka-shing (Hong Kong). His $10.6bn fortune isn't far short of Guatemala's annual GDP ($11.3bn). He is another Hong Kong property magnate, born into poverty in the neighbouring Chinese province of Guandong. He started out manufacturing plastic flowers. Now he has investments in the Orange telephone network and Felixstowe Docks.
Yoshiaki Tsutsumi (Japan). His present $9.2bn fortune is close to Sri Lanka's annual GDP ($9.4bn). But, once, he would have left Sri Lanka and dozens of other Third World countries far behind. According to Forbes, he was the world's richest individual but lost the title when Japanese property prices plummeted. His other big interest is in transport - he owns 40 per cent of the Seibu Railway.
Paul G Allen (US). His $7.5bn wealth is almost as great as the GDP of El Salvador ($7.6bn). He co-founded Microsoft with Bill Gates but left the company in 1983 when he developed Hodgkin's disease. Last year he put $500m into Steven Spielberg's new entertainment company, Dreamworks.
Kenneth Thomson (Canada). His $7.4bn fortune is only just beaten by Costa Rica's GDP ($7.6bn) The empire he inherited from his father, Roy Thomson, continues to flourish, despite his decision to sell his London newspapers, the Times and Sunday Times, to Rupert Murdoch in 1981. The Thomson Travel Group remains Britain's largest tour operator and he is now expanding into electronic publishing.
Tan Yu (Philippines). His $7bn fortune exceeds the annual GDP of Panama ($6.6bn). He is one of the world's largest landowners, whose property interests stretch from China to Las Vegas. He started out selling T-shirts in Manila but owned his own factory by the age of 22.
And here, more briefly, are the next 50 in the Forbes list:
Kwok Brothers (property, Hong Kong) $11.2bn
Theo and Carl Albrecht (discount retailing, Germany) $9bn
Hans and Gad Rausing (packaging, Scandinavia) $9bn
Johanna, Susanne and Stefan Quandt (BMW cars, Germany) $8.1bn
Haniel family (conglomerate, Germany), $8.1bn
John Werner Kluge (Metromedia, US) $6.8 bn
Wonowidjojo family (tobacco, Indonesia) $6.7bn
Rockefeller (John D) family (oil, US) $6.2bn
Carlos Slim Helu and family (conglomerate, Mexico) $6.1bn
Chung Ju-yung and family (conglomerate, Korea) $5.9bn
Kwek Leng Bang and family (property, hotels, Singapore) $5.7bn
Gerard Mulliez and family (retailing, mail order, France) $5.7bn
Robert Kuok (conglomerate, Malaysia) $5.7bn
Chen Yu-tung and family (property, Hong Kong) $5.5bn
Walter Haefner (car imports, software, Switzerland) $5.5bn
Mellon family (inheritance, US) $5.4bn
Ten Fong and Robert Ng (property, Hong Kong) $5.2bn
Yasuo Takei and family (consumer finance, Japan) $5.2bn
Michael Otto and family (retailing, Germany) $5.2bn
Philip Hampson Knight (Nike, US) $5.1bn
Eka Tjipta Widjaja and family (conglomerate, Indonesia) $5.1bn
Antonio Ermirio de Moraes and family (conglomerate, Brazil) $5.1bn
Liliane Bettencourt (L'Oreal cosmetics, France) $5bn
Merck family (pharmaceuticals, chemicals, Germany) $5bn
Silvio Berlusconi (media and other, Italy) $5
Mohamed Salim Bin Mahfouz and family (banking, investments, Saudi Arabia) $5bn
Lawrence J Ellison (Oracle Corp, US) $4.9bn
Lee Kun-hee and family (conglomerate, Korea) $4.9bn
Johnson family (US) $4.8bn
Masayoshi Son (software, publishing, trade shows, Japan) $4.6bn
Alice L Walton (retail inheritance, US) $4.6bn
Helen Walton (retail inheritance, US) $4.6bn
Jim C. Walton (retail inheritance, US) $4.6bn
John T Walton (retail inheritance, US) $4.6bn
Henkel family (chemicals, Germany) $4.6bn
Friedrich Karl Flick, Jr (investments, Germany) $4.5bn
S Robson Walton (retail inheritance, US) $4.5bn
Hearst family (newspapers, US) $4.5bn
Liem Sioe Liong and family (conglomerate, Indonesia) $4.5bn
Lan dolt family (pharmaceuticals, financial services, Switzerland) $4.5bn
Kirk Kerkorian (investments, US) $4.4bn
Richard Marvin DeVos (Amway, US) $4.4bn
Donald Edward Newhouse (publishing, US) $4.3bn
Samuel I Newhouse, Jr (publishing, US) $4.3bn
Jay Van Andel (Amway, US) $4.3bn
Dhanin Chearavanont and family (various, Thailand) $4.2bn
David Sainsbury and family (supermarkets, UK) $4.1bn
Boehringer family (pharmaceuticals, Germany) $4.1bn
Masatoshi Ito and family (retailing, Japan) $4bn
Iwasaki family (property, hotels, Japan) $4bn